Another odd interview question
 

Here's one for rumination: You're rolling down the runway, and past V1 you encounter windshear, such that you do not reach Vr. What do you do?

The prevailing train of thought is that if you don't take off, you're going to crash. Consequently, you firewall the thrust and rotate at whatever speed you manage before the end of the runway.

The other is that if you can't make Vr, you're going to crash, so should execute a high-speed abort. You may overrun the runway, but it's better to do so at 30 knots (or whatever), than at 130 knots.

Thoughts?

To me it would depend on where I was....short runway or long.

X

I wouldn't be so worried about not getting stopped by the end of the runway - with windshear overrunning the runway is a good outcome to me (although obviously not ideal). After you get in the air will you be able to climb is the real question? I'd be more afraid of a no to that answer than overrunning the runway.

Freeze up and panic!

Seriously, I think these type of interview questions are more about seeing if you can make a sound, defensible judgment call under stressful conditions than any "right or wrong" answer. Your answer will reveal much about your flight experience, training, and ability to make a decision and stick to it.

Obsess about answers to specific type interview questions like this, and you'll freak out when they ask you a question you didn't anticipate and prepare a canned answer for.

For the Trekkies: It's a Kobayashi Maru Test . .. "There is no right or wrong answer, it is a test of character."

Generally speaking, in the big airplane world a high speed abort is much more dangerous than taking an airplane into the air with a problem. There are certain circumstances where the airplane won't fly so the abort is called for. The question is is this one of those instances. More information is called for.

Military TOLD always includes a refusal speed. On dry runways that is generally higher than rotate which is usually go speed. Above rotate/go speed and below refusal you can still abort by the end of the runway. You might burn up the brakes and blow the fuse plugs but you will stop. I am still trying to wrap my head around civilian TOLD. V1 seems to be close to CEFS. I am still just concentrating on calling out the right things at the right time! :D

So to answer your question, it would depend on the scenario. Is it a small/big airplane? What runway and where? Obst? What kind of windshear, ie micro burst? What is the weather? Hopefully the interview question fleshed some of those questions out when posed to you.

All that being said, if you were close to V1 I wold stop and pray I wasn't at Guam.

At the gate I briefed... any problems after V1 I will take the aircraft into the air and we will climb to a safe altitude, troubleshoot and run any appropriate checklists, declare an emergency if necessary, and return to XYZ airport.

That would be my answer. V1 and Vr are usually so close together that if you come across V1 you usually are already at or within a few knots of Vr so do as you briefed and as you are trained. If your airspeed hits V1 and then degrades below V1 then you are below V1 and again do as you briefed and are trained.

We are talking about a split second decision here, so make your call and then stick to it....the only right answer is the one that leads to everyone getting off the airplane alive.

Its definately something to keep in your mind on a day where the DA is high....its hot and your heavy.

Depending on the length of the runway...balanced field length and all that stuff determines what you should do. In my opinion??? If the field is long enough...abort...I brief that after v1 one of the few things ill abort for is loss of directional control, which depending on the severity of the windshear could happen.

Though few and far between, their are instances where you will have to abort past v1 or sometimes even after vr. We used set and elevator jam at rotation in the sim for the lear 60. Crews had no choice but to abort. Just to show them that its possible that you may not have a choice.

The Boeing procedure is to continue the takeoff. Rotate at the 2000' remaining point regardless of airspeed. This has been the procedure we have taught at both UPS and Delta on the 737/757/767/747-400/777 fleets. With today's wx radar and predictive wind-shear systems it would be rare to be surprised by wind-shear. The crew probably would have made allowances for wind-shear advisories(i.e increased rotation speed based on RATOW, max thrust, different runway etc.). The key to the question is that you are above V1.

My companie's ops. manual addresses this case and states to initiate a normal rotation at least by the last 2000 feet before the end of the runway.

The DAL procedures specify that you would fire wall (ie cook) the engines and rotate with 2,000' feet of runway left even if you haven't reached VR. If you think about it this is the logical choice. Statics show that you are almost guaranteed to crash attempting to abort above V1, but may very well be able to fly under the circumstances. The ability to safely fly in that situation is, as someone said, an unknown, but it's less of an unknown that the likely outcome of the alternative. (aborting after V1, history shows an almost guaranteed crash)

This logic is further bolstered by the common guidance given to justify aborting after v1. "only if the aircraft is unable to fly" Well in this scenario you're not really sure about the flyability'. If the weather is so bad that you do have assurance that you can't fly then you shouldn't have been attempting a TO in the first place.

The Lear with the elevator jam at v1 is a no brainer and really a different discussion, as you would be certain the Lear would not fly. It is, however, a good example of a situation (however unlikely) that you would definitely abort after v1.

As you may have already figured out, there are many factors to consider.

Directly from the Airbus procedure:
-At takeoff
-If before V1
The takeoff should be rejected only if significant airspeed variations occur below indicated V1 and the pilot decides that there is sufficient runway remaining to stop the airplane
-If after V1
Call- “Windshear TOGA”
-Thrust Levers TOGA
-Reaching VR ROTATE
-SRS Orders FOLLOW

The reality is in most cases the V1 and VR speeds are higher than Vmu (Mininmum Unstick) as they are usually optimized for second segment climb performance. Put simply, the airplane will fly at speeds lower than V1 and Vr.

The only other factor that I consider is the calculated distance remaining after a reject is performed at V1- depending on the runway (say a 12,000' runway) I've seen as much as 3,000' feet remaining. As the Airbus procedure says, if you 'believe' that it is possible to stop, then stop. If you do not believe you will stop (e.g. KLGA) then GO!!

You are absolutely right about Vmu and its relation to V1 and Vr. However, from what you posted, it looks like you must be below V1 to even consider aborting. There is no mention of aborting in the "If after v1" section. It only lists it as a possibility in the "If before V1" section. So after v1, according to the procedure above, your beliefs don't enter into the discussion.... you just go. by:

-If after V1
Call- “Windshear TOGA”
-Thrust Levers TOGA
-Reaching VR ROTATE
-SRS Orders FOLLOW

No sir, you are wrong. Here is your Q3. Enjoy! :)

Sarcasm...

Two of my military airplanes didn't have refusal speeds. They had regular V1, VR, V2 speeds.

-Fatty

Why would you crash if you didn't make Vr ?

In some cases V1=Vr. In any case, Vr is 1.05 X Vmca. Then, once airborne, V2 is 1.10 X Vmca.

BTW, this stuff is very well covered in the Euro ATPL theory exam if you ever get a chance to view the books.

There's a lot of margin in these V speeds!

I've taken off hundreds of times where, had I gone OEI, my reaching the 35ft screen height at V2 was not assured and I knew it. Even so, takeoff is still legal!


If you abort after V1, you better have a good lawyer, if you're still alive!

If you reach V1, keep going.


AL

Completely off topic, while dead heading on the Boston shuttle Tuesday, a lady sitting next to me commented on the fact that she had been involved in three airlline accidents and a flight where a baby had been delivered. Specifically, one such incredible disaster happened when the airplane got airborne, encountered windshear, and then the pilots brought it back down and over ran the runway, broke up and burned. She exited via the overwing exits. Did I mention that she also looked like she owned 100 cats?

I just had a DA moment ... hahaha. reference 4m 34s YouTube - Lt. Napoleon

-Fatty

The primary concern with V1 and Vr is not second segment climb!
In most cases, you're only assured the screen height of 35ft at V2.
V1 is predicated on Vmbe and Vmcg. Vr may be equal to V1 but it's always greater than Vmu!



AL

Deez340,

What I showed there is what Airbus says and I find it a very useful guideline.

My personal thoughts I wrote at the end; i.e. if there is lots of ASDR it may be worth considering an abort. Therefore, most times I would be go oriented after V1. I've seen a sim demonstration of what even a 10 kts tailwind will do if an abort is performed from V1 and it was not pretty. You might stop it in time if you tried, but it's more likely the airplane will fly if you elected to go.

alvrb211,

Maybe I wasn't clear before, as I understand how and why the V speeds are done. However, with sufficient runway, the speeds are usually higher than the minimum required (to get off the ground) to allow the aircraft to accelerate to higher speeds on the ground to have better climb performance once airborne. i.e. for a given aircraft of the same config, weight and field conditions, the speeds will be higher for a longer runway than for a shorter one. My point was that sometimes a go decision is still best below V1 as the airplane is still quite capable of flying.

I've seen V speeds of (approx) 166, 170, 172 for a heavy A321 using Config 1on a long runway. If I encountered windshear at say 160 KIAS, depending on severity I am inclined to go TOGA and take it in the air. That bird does not stop well when heavy.

You have to beware of Vmcg if you're below V1

AL

Strange post don't you think?

Not sure why you use the "professor" moniker. This is basic stuff.

I'm not European. Why the reference? Do you fly with a lot of Europeans who, in your view, talk-a-big-game-but-can't-fly-for-crap, as you put it?

That's a pretty racist and bold statement. I'd feel just a little stupid after posting something like that on a public forum!

I'm not sure what nationality you are. Perhaps you don't like or respect Europeans, or European pilots, in general.

What "in your view" constitutes "talking a big game" or "being unable to fly for crap"?

AL

alvrb211,

Agreed, about Vmcg and Vmca for that matter, but on the A320 the highest of either is less than/equal to 110 KCAS. Though possible, not usually a factor at the V-speeds that I'm accustomed to seeing. If Vmcg/a is a factor, then a stop decision is the way to go especially since the speeds would be so low to begin with.

Agreed.

Good topic!

AL

Temp hijack....Dave Chael was a Tweet IP when I went through Vance in '87. What the heck was he doing there in '05? Reservist?

That is because, fatty, you are a Gucci boy. Everyone knows that the Gucci boys were never in the military. And let me guess, your other airplane was a C-21? Once again, not really in the military. :D

I guess I should qualify my remarks. Every airplane in the Air Force that I came in contact with had a refusal speed. I also taught SUPT for 12 years. That is a lot of TOLD discussions. The T-1 had S1 and Rot and Vr and CEFS and CEFL and VMCG and VMCA and a whole lot of other alphabet soup definitions.

ok, so as I read it... windshear right after V1 but before Vr.... wouldn't airspeed now be below V1 again in this scenario?

Could be. Especially if there's little or no exposure time.

AL

While I agree with you that the post was strange.. and I might add even over the top with some kind of underlying angst... it is not racist. People need to stop throwing that tag around so much.

Steve

this talk of Vmcg and Vmca is irrelevant if all engines are running.

if one has an engine failure on take-off with an windshear? the only discussion would be where the wreckage is located.

V1 - the aircraft might not be able to stop on the remaining runway/stopway after this speed
Vmu - the aircraft will liftoff
Vr - since it is above Vmu, the aircraft will also liftoff, and since it also a marginal amount faster than Vs, the aircraft will fly.
V2 - the aircraft would probably climb better at this speed than Vr

and ultimately, is holding any of these speeds in windshear realistic? since Vr is so close to Vs, and conveniently labeled, once can consider it the minimum. outside of that effective limitation, getting the aircraft to climb is the only concern.

That is exactly how they trained it on the 737-800NG at your school house in ATL when I went through with ATA. It worked every time and it made perfect sense. Next to my beloved TWA that was some of the best training I have been through.

Also, in some cases aborting after 80kts (high speed) have lead to negative out comes to some flights.

As always.

AL

It's always a good idea not to put any kind of moniker on a given race!

THAT'S what people need to stop throwing around! It's known as racism!

AL

Agreed it wasn't "racist". Nationalistic is more appropriate, but the remark had the same earmarks of ignorance, prejudice, discrimation, stupidity and unprofessionalism as a racist remark.

Excellent answer and agreed. Those types of questions are a test of judgment and decisiveness.

At my company, we're supposed to rotate with 2,000 ft of runway left as well, if we haven't reached Vr. However, this is a windshear adjusted Vr. If windshear is reported and likely, we make the new Vr the lesser of either the max wt for the planned runway Vr, or the Vr for our aircraft wt plus 20 kts.

So, it is likely that the airplane will fly, even if we haven't reached the adjusted Vr.

I would confer with the pilot-not-flying about the situation at hand. I would present the situation, any and all possible alternatives and outcomes, and ask him/her what he/she is comfortable with. I would also encourage said individual to express his/her feelings with regard to the situation at hand.

Upon discussing this situation with the non-flying pilot, I would then elect to go with the best course of action predicated upon a decision reached by all crew members so as not to come across as "old school", but rather as a CRM-trained professional who values the input from any and all available crew members. At that point I would elect commit to said decision attained through extensive use of CRM concepts and models.

That is how I would answer this question. The interviewer(s) is probably checking to see if you are a "loner" or a "team player". This answer certainly displays a commitment to CRM principles and communicates your ability to handle a serious situation without excluding the input from the rest of the crew. I think they would be very impressed.

Don't forget that good CRM includes a call to dispatch... getting a third opinion never hurts! :D

Wow, all that while rolling down the runway for takeoff. Impressive...

Did anyone check the WX prior to T/O?
Maybe this situation could have been avoided with some preflight planning.

I re-read the initial post and I recommend some you do so as well- it sure seems like a case of RTFQ. An interviewer asks about your decision on the takeoff roll and you begin to discuss dispatch and verbose CRM concepts? I think you would've just made it easier for other candidates to be considered.

Good point, we need to keep the entire team in the loop.

Their answers are probably boring - mine is much more entertaining. :D