Departure mins?

[172driver]

I am under the assumption that there are no takeoff minimums for aircraft operating under Part 91. Correct? Several of us have been discussing takeoff mins for 121, 125, 135 and we really opened up a can of worms. Eventually, people were trying to convince me that the 1/2 and 1 SM rule applied to turbojets operating under 91. I shook my head and left the discussion, seeing that we weren't getting anywhere.

OK. Now, what are the rules for departure under 121, 125, 135? I just need the takeoff mins, not the alternate reqs. From reading, I gather that std mins are: 1 or 2 eng= 1 SM and 3+ eng= 1/2 SM. Am I correct so far?

The next thing that got me was the back of the Jepps, which list the std mins as stated above. They also state that with adequate visual reference, required vis drops to 1/4 SM for all operators. I understand the definition of adequate visual reference but 1/4 SM seems like a pretty big drop from 1SM. Also seems like it makes the std mins pretty much obsolete. Why would one ever use 1 SM when they could just as easily use 1/4? Seems like you would always have adequate vis ref if you had 1/4 SM vis...

Why isn't the adequate vis ref discussed in the FAR's since it seems it is probably more widely used than the std mins?

Don't all 121, 125, 135 operations have ops specs anyway which supersede the regs? Are they more or less restrictive?

Also, why are the t/o mins for 121, 125, 135 operators discussed in Part 91 of the FAR's rather than the appropriate chapters?

Help! I know I came to the right place and that this stuff is probably pretty elementary to most of you but it's got me chasing my tail. Thanks in advance.

 

[Fr8Dog]

Standard takoff mins for 135 1or2 engine is 1sm vis. However most ops specs have below standard takeoff mins. Ours is whatever the lowest landing mins are, but not lower then 1800RVR since that is the lowest we can land ever. Some 135 operators can get as low as 600RVR takeoff mins, but it just depends on your ops specs.

 

[mike]

The FR8DOG is correct. We have 600 RVR mins with restrictions like crew training, controlling RVR and independent instruments with independant power sources.

What you are certified to do and what you feel safe doing are different things. You can take off zero/zero part 91, but would you take that chance?

Be safe.

 

[SkyWestCRJPilot]

I hope I get this right. For us adequate visual reference means Runway Center line markings, Runway Centerline lighting, Runway lighting, etc. The required items are listed on the Jepps under the departure procedures. A runway is required to have all of these available for us to take off at the 600 RVR limit. If one is missing, runway centerline markings (should the runway be snow covered is an example) then it increases to 1200 RVR I think. It lists these items on the Jepps like I said so I don't remember exactly. It also requires special aircrew training which we do in the sim. I also belive only two-pilot (or more) crewed airplanes are allowed to go as low as 600 RVR. Some runways from smaller airports don't have the required items (runway centerline lighting, etc.) so our takeoff minimums increase to the landing minimums instead. If the landing minimums are 1 1/2 miles then the 1 mile rule for 2 engines would be better than landing minimums (1 1/2 miles). What your friend said about turbojets having to follow the 1 mile rule is not right. When I flew freight in a C-210 out of MKC (Kansas City Downtown) we could take off if we had the landing minimums. Since there are lots of tall towers and buildings nearby the ILS landing minimums were 1 mile. One morning all the freight operators were waiting for the fog to burn off before we could leave and multiple corporate jets were departing since they were Part 91. The idea being that if you lose an engine right after takeoff (multiengine) you would be able to either come back and land at that same airport after doing an instrument approach, or be able to fly to another airport within 1 hour. Another example, sometimes this same freight operator had multiple airplanes on the ground that couldn't take off from their base airport where they originated due to vis below 1/2 mile (their takeoff mins at that airport). They had all the pilots takeoff empty (Part 91), and fly 10 miles away to the next closest airport which wasn't fogged in. They picked up their freight and were on their way. I may be off a little on some of this but I hope this helps some.

 

[cvsfly]

Part 91 should not just disregard published T/O minimums. Many come with an obstacle DP that needs to be followed, but otherwise could depart 0/0. Standard for 1-2 eng is 1 sm & 3+ is 1/2 for Part 135, 121, etc, but many operators have specific Operating Specifications that can lower that given the proper equipment/crew. I've always been unclear on Jepps "Adequate Visual Reference" figure. How is that determined and is this just nice to know stuff or does it pertain to certain operations?

 

[cl-65link]

The 666 rule for some 135 and 121 operators has somewhat of a caveat. That is, to depart with this vis., you must have a take-off alternate. This is defined as a alternate with weather at or above landing mins. within 1 hour flying time, single-engine and in still- air. For instance, when I used to fly out of MEM, we usually got LIT as our take-off alternate.

 

[172driver]

Ok, thanks all, we're getting somewhere. 91 and 121/135 Std mins are as I thought, ops specs generally 600 RVR with adequate vis ref.

Why is 1/4 SM with adequate vis ref published on the Jepps? Is this a reg? Terps? Why are any mins on the Jepps for that matter? Sounds like all 121/135 operators have their own rules anyway.

Do you guys get special plates published for your companies' ops specs or just apply the specs to the normal plates?

Why are 121/135 departure regs published in Pt 91? Certainly the departure alternate stuff isn't.

When might you not have adequate visual reference when vis is above 600 RVR? Snow is a good one. Does the rwy have to have CL lts per the regs or is that another ops spec?

What exactly is the 666 rule? 600 RVR is obvious but the rest...

 

[cl-65link]

666 rule= 600 touchdown, 600 mid-field, 600 roll-out. At some airports, one of these can be "missing" and you can still legally depart. Refer to the back of the chart.

 

[SkyWestCRJPilot]

We were allowed to use 500/500/500 instead of 600/600/600 for awhile. The sims were all set up at 5/5/5 so we were certified for it. Then they realized that at some of the airports we fly into you can't even taxi if this vis is below 600 unless your part 91 (Fresno for example). This created a lot of confusion so they just brought the lowest departure mins back up to 6/6/6.

Regarding why departure mins. is discussed under part 91, not 121 or 135, well I'm not sure except a lot of things that apply to 121 and 135 operations are found in part 91. Part 91 is kind of the basis for everything else and 121 and 135 are exceptions if you're flying under those regulations. Then Ops Specs (Operations Specifications) are the exception to 121 and 135. I'm not the government regulator/lawyer who wrote the regulations so I'm not sure why a lot of regs are where they are or written how they are.

About the special Jepps plates. The Jepps we have for departure are the basic ones I believe. We do have a few specialized plates for certain approaches, some with alternate missed approach procedures that allow us to get lower on an approach, but for the departure procedures on the back of an airport Jepp plate we use the basic one as far as I know. 172driver, do you use Jepps or NOS? It's been a long time since I used NOS.

 

[SSDD]

Skywest pilot,

Just want to clarify something you wrote a couple of posts back. Adequate visual reference does not require any of the items you mentioned, only that you are able to identify the takeoff surface. If I recall correctly, the majority of airports in the Skywest system don't have centerline lighting, yet they are approved for 1/4 mile takeoffs. What you stated may be a personal opinion, but not a restriction.