I'll bet this has been asked before

[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