PhilosopherPilot
Well-Known Member
On the whole it's safer to take an engine failure into the air rather than reject. System safety, not individual flight safety.
Sad Realization
- Thread starter Finhunter89
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jtrain609
Antisocial Monster
You've found us out. Part 121 drivers are nothing but a bunch of no talent ass clowns. I'd recommend you never come and work at a 121 carrier, because we're all obviously idiots.
PhilosopherPilot
Well-Known Member
Also, for my aircraft when you reject the autobrakes give you full reject braking. There isn't a "we have a long runway so less is needed" setting.
Hacker15e
Who am I? Where are my pants?
The -1 gives different braking techniques based on different speeds in the T-38.
jtrain609
Antisocial Monster
I don't think there are any airlines operating T-38's.
Hacker15e
Who am I? Where are my pants?
Not what I said.
I think your response was ridiculous, as you obviously have never operated with anything other than a BFL-calculated V1, and thus don't have any idea what it is like to do so using an actual runway length V1.
Your "we're too busy to have to do something different" is asinine. We all -- 121 pilots included -- do this with every other aspect of aviating airplanes. There's not something so unique about changing the way V1 is calculated that suddenly makes it so complicated that you can't understand how to use and apply it.
Hacker15e
Who am I? Where are my pants?
He asked me how I knew what to do, and I referenced the tech data that I've used to do it. Not sure what your snarky point is here?
Dugie8
Well-Known Member
Very good, that does not exist anywhere in the civvy jet world (part 25). That isn't a FAA thing, that is a Boeing thing, et al.
Part 25 says the brakes have to accelerate at 6 fps(squared) and be able to retain that energy, ie not fail. The mfgrs have decided how best to accomplish this.
Hacker15e
Who am I? Where are my pants?
This is circular logic.
Yes, I understand that this is what Part 25 says. Part 25 drives the testing and certification, and thus drives what is executed by people flying them.
Back to the beginning....why not compute using actual runway length.
jtrain609
Antisocial Monster
Let me get you up to speed real quickly; you're talking out of your ass about an operation that you've never done, with threats you've never seen, training you've never done, and operating cultures you can't comprehend. At some airlines, setting an abnormal flap setting has resulted in running off the end of the runway, and that's probably not as close as part 121 carriers have come to disaster when something non-standard has come up.
PhilosopherPilot
Well-Known Member
I'm not speaking for him here, but I think his point is that we have standardized procedures that are geared to the least common denominator. If the V1 that the system spits out is based on field length, fine, but we treat it the same no matter what.
Every flight is the same in terms of procedures. The details vary, but we do it the same way every time. It's a proven system. 121 is ultra safe.
PhilosopherPilot
Well-Known Member
Let me get you up to speed real quickly; you're talking out of your ass about an operation that you've never done, with threats you've never seen, training you've never done, and operating cultures you can't comprehend. At some airlines, setting an abnormal flap setting has resulted in running off the end of the runway, and that's probably not as close as part 121 carriers have come to disaster when something non-standard has come up.
Yeah, that was a scary close one.
Dugie8
Well-Known Member
Ok, I see what you are saying and to a point I agree. The point I think I'm not getting across very well is that, right now, we could do what you are suggesting but without a proven procedure on how to modulate brake inputs to remain within the limits of the brakes we are just spinning our wheels ( see what I did there).
I would WAG that any aborts above the max V1 of almost any relatively modern part 25 jet would quickly exceed the brakes ability to stop the aircraft without blowing the plugs, regardless of runway length. That isn't a part 25 thing, that is a mfgrs thing, ie BOEW vs payload payoff.
Now if there was a way to set the brakes to 25% and that would allow me to reject at 182 knots on a 10000 foot runway and my inputs were the same, I'm all for it.
I would WAG that any aborts above the max V1 of almost any relatively modern part 25 jet would quickly exceed the brakes ability to stop the aircraft without blowing the plugs, regardless of runway length. That isn't a part 25 thing, that is a mfgrs thing, ie BOEW vs payload payoff.
Now if there was a way to set the brakes to 25% and that would allow me to reject at 182 knots on a 10000 foot runway and my inputs were the same, I'm all for it.
Hacker15e
Who am I? Where are my pants?
?
What does any of this have to do with anything we're discussing here? You've completely lost me.
PhilosopherPilot
Well-Known Member
As to WHY they aren't calculated that way:
1. I have no clue.
2. If I were to guess, I'd say it doesn't add much reliability or efficiency to the operation, but could increase risk by moving closer to the max capability of the aircraft. As JTrain said, we don't often operate near the margins of aircraft capability. If we did, we would introduce more risk into the system.
1. I have no clue.
2. If I were to guess, I'd say it doesn't add much reliability or efficiency to the operation, but could increase risk by moving closer to the max capability of the aircraft. As JTrain said, we don't often operate near the margins of aircraft capability. If we did, we would introduce more risk into the system.
Situationally speaking, by the same token taking a sick airplane that has a fuselage fire or structural damage of some kind airborne, may be the difference between burning off the end of the runway, or piling it in 2 miles past the runway once airborne. Situations for aborting past V1 (while definitely not the norm) need to be briefed and understood why it would be done.
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Engine failure, yes, agreed. Numbers known and computed for those. As well as most "standard" emergencies or nuisances.
Hacker15e
Who am I? Where are my pants?
I understand this was driving your earlier comment, and could be a valid point.
If the risk here is "blowing the plugs" and having flat tires, that seems like an incredibly minor reason to use that as a yardstick compared to the risks involved with the V1-go, 4-segment single-engine climbout process required to continue after an engine failure.
Based on the airplanes I've operated, and the airspeed difference between a BFL-calculated V1 and an actual-runway-length calculated V1, and the areas of the brake energy chart where this would be an issue, it hardly seems like a reason to be the controlling factor.
Gents; rather than retreating to entrenched positions here because "that's the way it is", I'm asking a question about why. So far the "because it is safer" answers are mushy, feel-good, fact-free answers that have no factual data to support, and that type of information is what makes it an actual discussion.
I had a DPE for my Multi Commercial that was a retired Continental guy. He said that he would rather crash an airplane in to the trees at the end of the runway at 20kts, than to take a sick airplane in to the air and crash at 200kts 3 miles away. It gave me something to think about.
One would think that if it is safe to abort at 120kts on a 6000' runway, it should be safe to abort at 140kts on a 12,000' runway. At work, we brief that we will take off at V1, and that is exactly what I expect to do unless a wing falls off.
One would think that if it is safe to abort at 120kts on a 6000' runway, it should be safe to abort at 140kts on a 12,000' runway. At work, we brief that we will take off at V1, and that is exactly what I expect to do unless a wing falls off.