I'll bet this has been asked before

[A Squared]

Singlecoil,

There's 2 seperate questions: May you begin (or continue) the approach, and may you depart on the flight. The first is controlled by 135.225 and the second is controlled by 135.219. The original question is "May you depart?" What you may or may not do when you get there is only peripherally related to that question.

Example: Ignore the question of ceiling for a moment. Consider only visibility. If you depart for a destination when the observations and forcasts indicate visibility below your minimums at the time of your arival, you are in violation of 135.219. Never mind that the clouds might magically part before you arrive and your approach and landing are perfectly legal. The act of departing is a violation in itself. Now, the original question is: "Does ceiling *also* figure into the criteria to *depart*?"

 

[Singlecoil]

I just came over to part 135 from part 121. The other day a captain told me we couldn't depart for our destination because they were reporting and forcasting a cieling of 100 and 1/2 mile vis. (the ils mins were 200 &1/2)

Isn't visibility and not cieling controlling for dispatch? I told him that and he thought I was insane. I can't find the portion of the regs that backs up my view. Any thoughts?

A squared, I'm talking about this original question that was posed. Even if you consider ceiling, 100 is good enough, no? I say this since you can continue down to 100 agl if you have the approach lights.

You say they shouldn't have departed?

 

[A Squared]

Singlecoil,

OK, I see what you mean. Sorry for misunderstanding. Hmmm, well by that logic, you would never need any more than a 100 ft ceiling, even for Valdez (HAA 4200') Even though if Valdez is reporting 001 ovc, it doesn't matter how good the visibility is beneath the ceiling, you're probably not going to pick up the approach lights.

>>>"You say they shouldn't have departed?"

Honestly, I'm not sure. I've scratched my head about this a bit, and I've heard opinions from some fairly knowledgable persons, and I've still yet to hear something that is very convincing that supports the "ignore ceiling" position. I will say that I would be rather uncomfortable with the idea of departing for a destination with a forcast ceiling below my lowest MDA if a fed was looking over my shoulder. If you've got something that shows clearly that you *can* ignore ceiling when you depart, I'm all ears.

regards

 

[ksu_aviator]

I guess I need to update my profile, I'm actually flying 135 now, I use to fly 121. I don't have any text to back it up, just a verbal FAA interpertation. Sorry.

 

[SneakyJake]

I think that it is pretty standard to depart in this situation under 121. Any lower of a ceiling and you and your dispatch will probably make alternative plans. Refusal may cause a carpet dance. I find no reason to not go take a peak and land or go to the alternate and bus the pax. If there was a problem with it a POI somewhere would let us know. As for going to court if something goes wrong; they will use what ever they can assuming that you tried to land without the flight vis.

 

[HAL]

Not to beat a dead horse but...

I am one of those 121 guys that got furloughed back to a 135 company, and I'm having problems with 135.219.

Again, here it is:

No person may take off an aircraft under IFR or begin an IFR or over-the-top operation unless the latest weather reports or forecasts, or any combination of them, indicate that weather conditions at the estimated time of arrival at the next airport of intended landing will be at or above authorized IFR landing minimums.

My question, very specificly is this: When do you make the change between current conditions and forecast conditions to make your go/no-go decision. For instance say the forecast is calling for below minimums all day, but the current METAR shows it is well above minimums. Do you go? Does the flight time make a difference. What if it is only a 30 minute flight there? What about if it is more than two hours to get there?

The FAR states you use either the latest weather reports (METAR) or forecast (TAF) or any combination. So what do you do if there is a conflict between them?

Thanks for any help you can offer.

HAL

 

[avbug]

Hal,

The chief concern with this regulation is the ETA. When the regulation stipulates that any combination of weather reports or forecasts, it means just that. You may combine area forecasts, METAR's, TAF's, etc. Any official weather.

In this case, if you have a current report stipulating that weather is above minimums, you know what the weather is right now. If, however, you have a forecast showing the weather at ETA to be below minimums, you have a problem. You can't launch.

Below, I have a letter which was actually forwarded by the FAA administrator, regarding this issue. Specifically, it addresses Part 121, but the subject matter directly relates to your question, and does address your question. The question asks just what you have asked; can we launch with weather reports showing destination weather above minimums, even though forecasts at the ETA show it below. Weather 121 or 135, the answer is the same; no.

Before posting this letter, a quick comment. You indicated that you got furloughed "back" to a 135 operation. Your wording seems to imply that this is a step backward, a demotion, a lesser position. I suggest you consider an attitude check, and be grateful to be flying. You are not in a position that's beneath your true calling; you are fortunate to be flying an airplane, and that should be the end of it. Enough soapbox.

The letter:

April 26, 1990
Mr. Robert J. Aaronson

Dear Bob:
Thank you for your letter of October 20, 1989, concerning the Federal Aviation Administration's (FAA) interpretation of Section 121.613 of the Federal Aviation Regulations (FAR). Your letter and its attachments have been carefully considered, and we regret that we could not respond more promptly.

In your letter you request that the interpretation of Section 121.613 by the Office of the Chief Counsel dated February 28, 1968, be "withdrawn." The Office of the Chief Counsel has advised me that the 1968 interpretation states, "We are of the opinion that the language of Section 121.613 is clear and that weather reports or forecasts or any combination thereof which indicate that weather conditions ... will be `occasionally' or `intermittently' below authorized minimums would not satisfy [the] requirement of Section 121.613 for weather conditions `at or above' authorized minimums for dispatch or release to that airport." You make this request because you believe that the interpretation significantly affects the schedule reliability of your member airlines and requires more fuel to reach available alternate airports, causing aircraft performance penalties.

Your belief is that the language and intent of Section 121.613 are much broader than interpreted by the Office of the Chief Counsel. You interpret the main body of a weather forecast to be an estimate. You also interpret any conditional language" that may be in the "remarks" section of a weather report or forecast as only expressing a level of uncertainty about the main body. Examples of conditional language are "occasionally," "chance of," "briefly," and "intermittently." In short, your conclusion is that the main body of a weather report or forecast should control and render insignificant any conditional language in the remarks section.

We are puzzled by the technical analysis which you have attached in support of your request. Basically, you assert that the frequency with which observations actually occur as forecast by the "remarks" section is very low. For example, you state in your Attachment 2 on page 2 that "where conditional language is used by NWS forecasters for ceilings, no ceiling was observed in 54 to 67 percent of the cases." This is not what scientists Lerner and Polger said in their scientific paper that you provided as your Attachment 3. Their Table 3 shows that the ceiling that was forcasted in the conditional remarks section did not occur between 54 and 67 percent of the time. Table 3 does not show that there was "no ceiling observed" in those cases, but rather that the forcasted ceiling did not occur. Since the conditional probabilities as defined by the National Weather Service apply only to weather conditions which are expected to occur less than 50 percent of the time, the data of Lerner and Polger reflect good skill on the part of the forecasters. We cannot see how a confirmation of the high quality of the aviation weather forecasts provided by the government supports your request to withdraw our interpretation.

We appreciate and understand your concerns with §121.613. However, after careful review of the interpretation and applicable sections of the FAR, the Office of the Chief Counsel and the Associate Administrator for Regulation and Certification have advised me that they do not believe that conditional language used by the National Weather Service (NWS) should be deemed to be overridden by the main body. The interpretation is, in their view, completely consistent with the language of the regulation, and they have found nothing in the regulatory history of §121.613 to indicate that the interpretation is incorrect.

You state in your letter that the interpretation has been overtaken by significant advances in technology such as weather satellite imagery and dial-up access to weather radar. You also state in your letter that this advanced technology can provide information to the pilot and dispatcher that was not available in 1968 when the interpretation was made.

The FAA clearly encourages development and application of advanced technology. However, to ensure safety, that advanced technology must be proved to be reliable. The current regulations require that weather reports be prepared by specific sources (e.g., the NWS or a source approved by the NWS) that use technology that has been proved to be reliable.

The Office of the Chief Counsel and the Associate Administrator for Regulation and Certification have also advised me that the best way to amend the rule to reflect advances in technology is through the rulemaking process. At any time, ATA may petition the FAA for rulemaking according to the procedures in §11.25 to suggest rule language that will provide for advanced technology. The rulemaking process will provide an opportunity for comments by parties who have knowledge of the subject and who provide the FAA with facts and opinions regarding the proposed advanced technology. These comments, facts, and opinions will be combined with the agency's expertise to make informed rulemaking decisions concerning the reliability of proposed advanced technology.

Your final statement is that the interpretation reflects an incomplete understanding of the dispatcher/pilot decisionmaking process when considered in context with §121.649 through §121.655.

The Office of the Chief Counsel has reviewed §121.613 in context with §121.649 through §121.655. Section 121.655 provides, in pertinent part, that "[C]eiling and visibility values in the main body of the latest weather report control for VFR and IFR takeoffs and landings and for instrument approach procedures . . . ." Therefore, §121.655 applies weather criteria in the main body of the latest weather report to operations (takeoffs, landings, and instrument approaches; at the time those operations are conducted. However, §121.613 applies weather criteria in a weather report or forecast to dispatch of an aircraft. Dispatch of an aircraft contemplates that landings or instrument approaches will be conducted at some future time. Because of this distinction, we believe that the interpretation is also consistent with the language of the various sections of the regulation that you cite.
If you believe that §121.613 should be changed to allow the main body of a weather report or forecast to control the aircraft dispatch requirements (such as provided in §121.655 for takeoffs and landings), we again recommend that you use the procedures under §11.25 of the FAR to suggest the rule language.
Meanwhile, if you have specific problems regarding particular carriers, please feel free to have your staff contact Anthony J. Broderick, Associate Administrator for Regulation and Certification, at (202) 267-3131. He and his staff will be glad to discuss those specifics with you.

Sincerely,

(signed) Jim

James B. Busey
Administrator

 

[avbug]

Second Legal Interpretation

This one also is a response to a question about Part 121. However, the same reasoning and policy applies to dispatch under Part 135, with respect to the use of forecasts and weather reports, and is applicable to the question at hand.

October 6, 1989
Mr. David P. Quinn

Dear Mr. Quinn:

This is in response to your letter of June 27, 1989. Each of your questions is set forth below and in followed in each case by our interpretation of the Federal Aviation Regulations (FAR) as the regulations apply to your inquiries.

FAR 121.613 reads in pertinent part:

"121.61 3 DISPATCH OR FLIGHT RELEASE UNDER IFR OR OVER-THE-TOP. Except as provided in 6121.615, no person may dispatch or release an aircraft for operations under IFR or over-the-top, unless appropriate weather reports or forecasts, or any combination thereof, indicate that the weather conditions will be at or above the authorized minimums at the estimated time of arrival at the airport or airports to which dispatched or released."

Question #1:

"1. Is a Part 121 Certified Carrier (operating either under domestic, flag, or supplemental rules) legal to dispatch a flight under IFR to a destination airport when the conditional portion of the terminal forecast indicates the weather will be below landing minimums at the ETA?

Example: Newark ILS 4R Minimums: 200 ft and 1/2 mile
Newark Forecast: 7 OVC 2F CHC 7 OVC 1/4F
--------- -------------- "
MAIN BODY CONDITIONAL

Answer to Question #1:

Subpart U of the FAR prescribes dispatching rules for domestic and flag air carriers and flight release rules for supplemental air carriers and commercial operators. Section 121.613 in Subpart U can be traced back to 1936 when it was originally promulgated as Civil Air Regulation (CAR) 61.71090. It was recodified approximately 19 times since its inception and was recodified in several different parts/sections of both the CAR and the FAR. In 1963 this section was amended from "weather reports AND forecasts" to "weather reports OR forecasts." This change allowed individuals to use either weather reports or forecasts, or any favorable combination of the two, in order to discern whether the weather at the destination airport would be above minimums.

The rationale behind the current regulation is that as long as one can show a combination of weather reports or forecasts indicating above minimum weather conditions at the estimated time of arrival (ETA) at the destination airport, the flight may be dispatched or released. However, the converse is also true, that when any combination of weather reports or forecasts show below minimum weather conditions at the destination airport at ETA, the aircraft may not be dispatched or released.

The FAA has consistently provided interpretations that a weather report or forecast does not satisfy the regulatory requirements of Section 121.613 when the weather report or forecast contains phrases reflecting that weather conditions at the destination airport at ETA may be at or above the required weather minimums and it also contains phrases reflecting possible below minimum weather conditions at the destination airport at ETA. Therefore, since the weather report or forecast as described above is not indicative of above minimum weather conditions, it is not sufficient to allow dispatch or release of an aircraft. Additionally, these interpretations found that Section 121.613 is not satisfied when forecasts or weather reports state that the weather conditions will be "occasionally," "intermittently," "briefly,," or "a chance of" below minimum weather conditions at the intended destination at ETA.

Question #2:

"Does it make any difference if the conditional portion is preceded with other conditional statements such as, "occasionally", [sic] "briefly", [sic] "intermittently" or "variable" [sic]?"

Answer to Question #2:

No. Please see the answer to Question #1.

Question #3:

"With reference to FAR 121.619, it states that a second alternate must be listed in the dispatch release if both the destination and the first alternate airports are forecasting "marginal" weather conditions. For purposes of this regulations, what is considered "marginal" [sic]?"

Answer to Question #3:

The origin of FAR 121.619 can be traced back to 1936 and Part 61 of the CAR. Prior to 1954, the rules concerning scheduled interstate air carrier certification and operation were contained respectively in Parts 40 and 61 of the CAR. In 1951, the FAA proposed in Draft Release 51-6 to consolidate these rules into Part 40, "Scheduled Interstate Air Carrier Certification and Operation Rules." Draft Release 51-6 was codified as Part 40 and after several postponements, became effective on April 1, 1954.

Section 40.181 of Draft Release 51-6 entitled "Alternate airport for destination - IFR" stated in pertinent part, "(a) For all IFR or over-the-top operations there shall be at least one alternate airport designated for each airport of destination and, when the weather conditions forecast for the destination and first alternate are marginal, at least one additional alternate airport ..." Section 40-181 of Draft Release 51-6 was designated as Section 40.389 in Part 40 and, by an amendment to the FAR effective April 1, 1965, Section 40.389 became Section 121.613 when Part 40 was replaced by Part 121.

The preamble to Part 40 in 18 Federal Register (FR) 2267 dated April 23, 1953, in discussing Draft Release 51-6 and Section 40.181(a) stated "Considerable comment has been received concerning the reference in Section 40.181(a) concerning the designation of a second alternate when the weather conditions forecast for the destination and the first alternate are `marginal.' This comment indicated that the word `marginal' is not sufficiently definitive and that the language contained in this section does not establish an unambiguous standard for air carrier operations. The Board recognizes that this comment may have merit but is of the opinion that some provision should be contained in Part 40 in recognition of marginal weather conditions. It is intended, therefore, that additional consideration be given this matter and an appropriate alternative proposal be circulated in the near future."

Since "additional consideration" has not been given the term "marginal" and since an "alternative proposal" has not been developed, we cannot give a definitive answer to your question. However, generally, when interpreting the FAR, no magical formula or semantic insight is necessary and, unless the word is otherwise defined, each word should be given its plain and ordinary meaning, that is, its dictionary definition. Webster's Third International Dictionary defines the word marginal in pertinent part as "4a: close to the lower limit of qualification or acceptability." Therefore, when the weather conditions for the destination and first alternative are close to the lower limits of weather conditions required for landing at the destination airport at ETA at least one alternate must be designated.

If you feel the rule should be changed, you may petition the Agency for rulemaking in accordance with Section 11.25 of the FAR. This letter has been coordinated with the Office of Flight Standards Service here in FAA Headquarters.

We hope this satisfactorily answers your inquiries.

Sincerely,

Donald P. Byrne
Acting Assistant Chief Counsel
Regulations and Enforcement Division

 

[avbug]

Third Legal Interpretation

Hal,

This is probably more information than you wanted, but it's best to be clear. This interpretation addresses both Parts 121 and 135, and makes clear the fact that the viewpoint of the Administrator is the same for either part, regarding the appropriate use of weather forecasts.

In this case, several scenarios are presented. One, is familiar. It involves dispatch when present weather indicates good, while forecasts indicate otherwise. The same question you asked. Another scenario is just the opposite, however. In this one, current weather is reported below minimums, but destination weather is forecast to be above minimums. In this case, because the operative condition is ETA, the flight may go...it's forecast to be above minimums.

I think the central theme to your question, if I understand it correctly, is weather or not a current hourly report can be substituted for a forecast, as the regulation stipulates that any combination may be used. The answer is that it can't, because the hourly report says nothing about the estimated time of arrival. It only speaks to current conditions. Only applicable reports can be used. One wouldn't use a report for another airport, and one can't use a report for another time.

Another way to think of it is this: destination weather is forecast to be below minimums. Can we dispatch if a METAR that's five hours old shows it being above? No, we can't. Likewise, we can't dispatch if the forecast shows weather below minimums (in say, two hours, or even a half hour), but current weather says it's fine...because current weather will be two hours old when we arrive (or a half hour, in the case of a short flight).

The Legal Interpretation:

July 18, 1984
Mr. C. D. Weatherly

Dear Mr. Weatherly:

This is in response to your request of November 4, 1983, in which you inquire into Federal Aviation Regulations (FAR) dealing with weather landing minimums at destination and alternate airports. You inquire into the following four proposed operations:

1. Proposed estimated time of departure (ETD) - 1545
Proposed estimated time of arrival (ETA) - 1615

1455 Destination sequence report - WOXOF
1600 Destination terminal forecast - C900VC20

2. Proposed ETD - 1545
Proposed ETA - 1615

1455 Destination sequence report - M900VC20
1600 Destination terminal forecast - WOXOF

3. Proposed ETA - 1630

1555 Alternate sequence report - WOXOF
1600 Alternate terminal forecast - 900VC20

4. Proposed ETA - 1630
1555 Alternate sequence report - M900VC20
1600 Alternate terminal forecast - WOW

You ask if the above operations can be conducted under PAR Parts 121 and 135 when the weather forecast calls for conditions at or above minimums but the hourly sequence reports indicate that weather conditions are below minimum (examples 1 and 3). You ask also about the situation where the forecast is for conditions below minimums but the hourly sequence reports indicate that weather conditions are at or above minimums (examples 2 and 4).

FAR Section 121.613 states, in pertinent part, that an aircraft cannot be dispatched or released for operations under IFR or over-the-top unless appropriate weather reports or forecasts, or any combination thereof, indicate that the weather conditions will be at or above the authorized minimums, AT THE ESTIMATED TIME OF ARRIVAL at the airport(s) to which the aircraft is dispatched or released. Section 135.219 requires that in order to take off and operate an aircraft under IFR or over-the-top, the latest weather reports or forecasts, or any combination of them, must indicate that weather conditions AT THE ESTIMATED TIME OF ARRIVAL at the next airport of intended landing will be at or above authorized IFR landing minimums. With regard to alternate airports, Section 121.625 states, in pertinent part, that no person may list an airport as an alternate airport unless the appropriate weather reports or forecasts, or any combination thereof, indicate that the weather conditions will be at or above the alternate weather minimums specified in the certificate holder's operations specifications for that airport WHEN THE FLIGHT ARRIVES. Similarly, Section 135.221 requires that in order for an airport to be designated as an alternate airport, the weather reports or forecasts, or any combination of them, must indicate that the weather conditions will be at or above authorized alternate airport landing minimums for that airport AT THE ESTIMATED TIME OF ARRIVAL.

The above cited regulations clearly indicate that the critical time period for purposes of determining whether an aircraft can be dispatched or operated under IFR conditions or whether an airport can be listed as an alternate is the estimated time of arrival. Weather forecasts which indicate that conditions will be at or above minimums at ETA are sufficient for operations under FAR Parts 121 and 135, even if hourly sequence reports state that weather conditions are currently below minimums. It follows that weather forecasts which indicate that conditions at ETA will be below minimums are not sufficient for such operations, despite what hourly sequence reports may indicate.

In your letter you ask if FAR Section 91.83(c) is inconsistent with the regulations cited above, and vice versa, with regard to requirements concerning weather landing minimums at alternate airports. You point out that Section 91.83(c) speaks to "weather forecasts" as controlling proposed operations, while the other regulations speak to "weather reports and forecasts" in their requirements. Section 91.83(c) provides, in pertinent part, that no person may include an alternate airport in an IFR flight plan unless current weather forecasts indicate that, AT THE ESTIMATED TIME OF ARRIVAL at the alternate airport, the ceiling and visibility at that airport will be at or above certain minimums. The critical time period for purposes of determining whether an airport can be listed as an alternate pursuant to Section 91.83(c), is the estimated time of arrival. Section 91.83(c) and the above cited regulations are consistent for this reason.

With regard to the examples in your letter, proposed operations 2 and 4 could not be conducted since weather forecasts indicate that conditions at ETA will be below minimums. On the other hand, proposed operations 1 and 3 could be conducted pursuant to Sections 121.613, 121.625, 135.219, and 135.221 since weather forecasts indicate that conditions at ETA will be at or above minimums. However, the certificate holder must also comply with FAR Sections 121.101, 121.621, 121.623, and 121.655 in conducting those operations.

We trust that this information answers your inquiry.

Sincerely,

John H. Cassady
Assistant Chief Counsel
Regulations and Enforcement Division

 

[avbug]

Fourth Legal Interpretation (dead horse)

Hal,

This one specifically deals with Part 135. It's older, and the specific regulations to which the author refers have been recodified (you'll find them under different reference numbers, now), but the interpretation is consistent, and relevant, and still stands. Also of value here is the statement that this has been the consistent interpretation for many, many years.

April 29, 1977

IN REPLY REFER TO: AGC-22

SUBJECT: Interpretation of Descriptive Phrases in Weather Forecasts

FROM: Acting Assistant Chief Counsel, Regulations & Enforcement Division, AGC-20

TO: AEA-7

This is in response to your letter of April 8, 1977, wherein you raised the conflict between past legal interpretations and the May 1976 General Aviation News pertaining to the designation of an alternate airport when part of a weather forecast indicates that conditions will be above minimums at the estimated time of arrival, but phrases such as "occasionally", "variable", or "a chance of", conditions would be below minimums, are also contained in the relevant forecast.

As you indicated, the response to Mr. Branagan contained in General Aviation News was incorrect. In addition to the ANE-7 interpretation of 121.625 (February 5, 1975) and the AEA-7 interpretation of 135.109 (April 4, 1974) which you provided us, we enclose a copy of an AGC-22 interpretation of 121.613 (February 28, 1968) for your information.

All of these interpretations are consistent and hold that forecasts which state that weather conditions will be "occasionally", "intermittently", "briefly", or "a chance of" below minimum conditions at the estimated time of arrival do not satisfy the requirements pertaining to the dispatch or release of an aircraft to its destination airport under 121.613 and to the selection of an alternate airport under 121.625 and 135.109. These interpretations would apply with equal force to 135.105 relating to the selection of a destination airport and 91.83(c) relating to the selection of an alternate airport. All of the cited provisions specify that a particular operation cannot be conducted unless weather reports or forecasts indicate that the weather conditions at the intended destination or alternate will be at or above the authorized minimums at the estimated time of arrival. Such phrases indicating that conditions might be below minimums at ETA, even though part of the forecast indicates that conditions may also be at or above minimums at the ETA, are not sufficient for operations governed by the above regulations.

As a result of your letter, we have recommended that Flight Standards make an appropriate correction in the General Aviation News and that all future regulatory interpretations appearing in this magazine be coordinated with AGC-20 prior to publication. We have also requested written regulatory interpretations (either in letter form such as that given by Inspector Birnbach of the JFK ACDO or as contributions to other aviation publications) to clear such responses with the Regional Counsel's office under all circumstances. We also recommend that your office take appropriate steps to correct Inspector Birnbach's letter of March 8, 1977 in addition to informing other Eastern Region facilities of the need to coordinate all written regulatory interpretations with your office.

/s/
NEIL R. EISNER

Enclosures

 

[HAL]

avbug,

Thanks for all the info. I think it answers my questions, but I'm still left with just a little nagging doubt about a really short flight where you know (or can even see) that the weather is fine, even though the forecast calls for below minimums - and the question is - can you launch? I'm still a little confused since the FAR says the 'current observations or forecasts or any combination of them' for the ETA. Just wondering about how long the current observation is good for since the FAR says you may use that in the decision making process.

As for my attitude about flying 135, I was taken a little aback by your comment. Yes, I am certainly greatful that I have a flying job and am able to stay current. Most of my friends that are furloughed from Hawaiian are not flying. And anyone who knows me knows that the last thing I would want to do is denigrate any branch of aviation or the people who work there. Flying in Alaska is more fun and challenging than I ever did at Hawaiian, and the scenery is unsurpassed. The 'furloughed back to 135' comment was concerning the 50% cut in pay, bad weather, lack of jumpseat priviliges (while my family is 1300 miles away), and other things I deal with here that I didn't have to at Hawaiian. For four months after the furlough and before coming up here I was flight instructing, and loved every minute of it, even though the pay was far less than the 135 job. I had no complaints then.

I'm sorry if I offended anyone with that comment. I certainly didn't mean it.

HAL

 

[avbug]

Hal,

Not at all. I didn't intend to be judgemental, only to query. All too often I meet folks who have the "props are for boats" attitude, and it irks me. Obviously that doesn't apply to you.

If you're on a very short flight, and current weather reports show the destination being open, then it's probably doable. If the weather is questionable at all, however, then you're going to have a hard time justifying launching.

The FAA has interpreted the regulation to mean that even the suggestion that the weather might occasionally be below minimimums is enough to prevent the launch, when the weather speaks to the estimated time of arrival. If you're going to take off and be there in five minutes, and can see the airport, and see that it's clear, and the current weather advises so, that's a different matter. An official weather forecast for the ETA stating otherwise, however, is the show stopper.

From a practical point of view, of course, if the weather is questionable or forecast to be below minimums, is there any reason that one should launch?

A current weather report is valid for the time it's reported, only. It doesn't imply weather in the future; the forecast is for that. We've all seen weather that's well below minimums jump up to VFR in short period. Sometimes it's frost on a transmissiometer, or celiometer, other times it's really the weather changing that fast. Other times, we've all seen the weather drop and change suddenly. All we can go by is the forecast, and the FAA has determined that if the forecast even hints that the weather may be below minimums, we can't go.

 

[HAL]

avbug,

Thanks again for the info. The whole subject came up because the forecasts here in northern Alaska are notoriously inaccurate. If the flight is more than an hour away, even if the current conditions are clear I understand the restriction on launching the flight. However since some of our flights are less than an hour, and the FAR 135.219 states that you can use the current conditions or forecast or any combiation (emphasis added) to decide whether to go, there has been a lively debate among our pilot group as to whether (and when) you can use the current AWOS report to supercede the TAF.

Thanks again for the input. Your responses will be printed out and I'm sure will add a lot to the ongoing discussion.

HAL

 

[avbug]

Strictly interpreted, consider a current weather report as being valid for the exact time of issuance, backward...in other words, it carries no weight for the purposes of forecasting. If you hold a TAF or other forecast that indicates weather below minimums for the ETA, even if it just hints at it, it outweighs any actual report you have in hand.

When the regulation was written (and this is discussed in the legal interpretations and letters), the intent was to prevent launching if a forecast even suggests weather will be below minimums. As the forecast applies to ETA and a weather report does not, the forecast takes precedence, and outweights any current report.

Another interpretation which I did not post, regards company reports. In that case, an aircraft that was equipped for known ice departed into conditions of forecast ice. When no ice was encountered, a radio report was made to the company. Company aircraft not equipped for flight into known ice were then launched, and encountered ice. The Chief Legal Counsel noted that the report by the company aircraft that ice was not encountered was not an official weather report, and did not serve to help the case of the other aircraft that launched into those conditions.

This has applicability in this case, with respect to unofficial reports. For the purpose of forecasting, a weather report (hourly SA, METAR, Tower observation, etc) does not take the place of a forecast, nor can it be substituted, because it is not a forecast. It is valid only for the exact moment it's issued, and doesn't presume to know the future. A company report is also unofficial, and cannot be used.

Only an official weather forecast will serve for future use, such as in the case of an ETA.

Where the regulation identifies any combination of forecasts and reports, it doesn't imply that one can pick and choose which ones to use, and which ones not to use. In other words, if weather reports (METAR) indicates weather above minimums at 0900, and your ETA is 1000, and the TAF shows weather below minimums at 1000...you may not use the METAR because it appears more favorable. The fact is that information exists from an official source that shows the weather may be below minimums, and that is all that is sufficient to establish the inability to launch due to 135.

The third legal interpretation above (July 18, 1984) establishes that forecasts overrule hourly sequence reports when the forecast shows the potential for weather to be below minimums, but the hourly reports show it presently above minimums. Again, the hourly reports do not speak to the future, where a forecast does, and takes precedence.

Conversely, the July 18 interpretation also stipulates that where an hourly report may show weather below minimums, a forecast showing it above minimums is sufficient to permit release by dispatch.

 

[HAL]

avbug,

I've read the documents you posted again, and I agree that the forecast supercedes the observation. But my biggest problem is why then does the FAA list 'observation or forecast' as how to decide. Why don't they just say 'Forecast' and be done with it, instead of muddying the waters by keeping the 'observation' in there?

Sometimes you just gotta love those government regulation writers.

HAL

 

[cubpilot]

Celing vs vis

Check your op specs you will likely see that destination ceiling (& vis) are both controlling to depart and to begin the final approach. Note also if the captain has less than 100 hours PIC, his and your minimums are razed by 100 and ½ mi.

 

[avbug]

You have OpSpecs showing ceiling being controlling??

 

[HAL]

cubpilot;

Which section of your opspecs list ceiling as controlling? I've been through my current (135) and Hawaiian (121) opspecs and can't find anywhere that lists it that way.

HAL

 

[cubpilot]

I flew for a regional airline from 1985 to 1989. I do remember ceilings counting for the weather at destination, in the decisions you make, prior to takeoff and before beginning the final, but not at MDA or DH. If I can find my old op specs I’ll look it up. Some of these other posts were about FAA interpretations; maybe we had a FAA interpretation that made it so for us. You do what yours says, if its not in there its not in there. You had a captain telling you that ceiling counted. Ask for some instruction on how to find the citation. What does your Chief Pilot say? Other Captains?

 

[avbug]

Visibility is controlling. Specifically, where available, the TDZ visibility is controlling. Ceiling is not controlling. However, where ceiling lies below minimums, one may not reasonably be expected to obtain the adequate visibility for the approach, and will provide a limiting factor. It is not controlling.

In the legal interpretation below, David L. Bennet provides insight into the concept of what is controlling. This statement does not specifically provide direction on a Part 135 operation. However, the letter is applicable in general.

March 10, 1986

Mr. Larry K. Johnson

Dear Mr. Johnson:
This is in response to your letter of February 6 requesting an interpretation of Federal Aviation Regulation (FAR) Part 91, Section 91.116.

Specifically, you request clarification of the term "flight visibility" in connection with the requirement in FAR 91.116(c) that an aircraft not be operated below a published decision height or minimum descent altitude if the flight visibility is less than the visibility prescribed in the standard instrument approach procedure being used. The question arises as to whether descent below the DH or MDA can be made when the runway visual range (RVR) is reported at less than the published minimum RVR for the approach but the flight visibility is greater than that minimum.

The flight visibility is controlling. If the flight visibility exceeds the published minimum for the approach, than the pilot may proceed as long as the other requirements of paragraph 91.116(c) are met regardless of the reported RVR. The National Transportation Safety Board (NTSB) has upheld this interpretation in several enforcement cases. However, the pilot's judgment of flight visibility is not necessarily conclusive if there is a question as to the actual flight visibility conditions at the time of the approach. Reported visibility and other evidence of record may be considered by the Federal Aviation Administration and the NTSB in determining the actual flight visibility.

Enforcement action would be taken only in those cases in which the pilot could not reasonably conclude that flight visibility was at or above approach minimums, but the pilot nevertheless proceeded to land or descent below DH or MDA.

Sincerely,

David L. Bennett
Manager, Airspace and Air Traffic Law Branch
Regulations and Enforcement Division