Perspectives

US Airways Express runs off the end of runway in Charlotte, WV.
http://www.wvgazette.com/News/201001190526

Some of you may have seen this in the news, however it didn't get all that much attention. I'm quite shocked by this considering that lately you can't fart on an aircraft without 7 news reporters there to cover the action.

"Roger Fuddlebottom here, at the center of the blast scene! I can't tell if the tandori chicken was to blame or perhaps the beef and cheese enchilada. But, it sure smells like ass! Back to you in the studio!"

"Thank you, Roger, for that epic report. Stay tuned for more details as this flatulation terror story unfolds, here on Browneye Witness News."

So, in case you hadn't heard, there was a regional jet (CRJ200) that aborted a take off down in West Virgina. Based on what was written in the above article, no one was hurt. The article isn't bad, however, it only addressed what the passengers experienced. I suppose, that's what most people are looking for anyways in such stories. If everyone lived and no one was hurt, everything must be OK.

From a pilot's perspective, however, we don't yet know if this crew indeed acted correctly. We can say that they didn't screw the pooch. No passengers were hurt or killed. However, they still may have gotten it wrong.

Allow me to explain...

There are two key questions that come about in this case after, "Is everyone OK?"

1.) At what speed was the abort initiated?

2.) What caused the abort?

The first one might not seem to be very relevant to the average person. However, to a pilot, this is extremely important. Perhaps, even more important than even what caused the abort. Like many times before, it will take some time to get there.

First, there are certain speeds that are calculated for each and every take off in the airline world. These are:

V1: Action speed (recently renamed from "decision speed")
Vr: Rotation speed
and
V2: Take off safety speed

In the interest of full disclosure, these are spoken as, "Vee-won", "Vee-Arr" and "Vee-too." V1 is almost always less than Vr, however V1 and Vr can be equal. V1 can never be greater than Vr. V2 is always greater than both V1 and Vr.

A standard take off goes as follows: Accelerate down the runway, reach V1, then Vr. At Vr, begin to pull back on the yoke and raise the nose off the runway, followed by the main gear and you're on your way. You continue to climb while retracting the gear and flaps, etc. That's the basic idea.

Now, V1 is the key here. If you haven't yet reached this speed and a serious malfunction were to occur, the take off can be safely aborted and the aircraft stopped on the remaining runway. (Note: clearways can legally be used here but that's beyond the scope of this post.) If you have accelerated past V1, the take off roll will be continued and the aircraft will be able to continue accelerating to V2, then rotate and leave the ground with the remaining runway, clearing all obstacles, etc, etc. The big point is that after V1, you might not have enough runway to decelerate the aircraft to a stop should you attempt an abort.

This is why runways seem to be longer than needed. With all engines operating, you will have plenty of runway for take off. BUT, the regulations state that you must have enough runway so that you can still safely take off if you lose an engine after reaching V1. Ever hear of an aircraft being "weight restricted?" This doesn't mean that just the weight of a few more passengers will make the aircraft too heavy to fly. It means that the aircraft, at it's current weight, will not meet the accelerate-stop and accelerate-go distance requirements for the given runway and atmospheric conditions should an engine fail at V1.

Now, as many of you know, the FAA seems to be stuck in the past sometimes. (Don't believe me? Take the ATP written exam and see all the questions that mention the DC-3.) The regulations I'm talking about here are based on the worst case scenario being an engine failure at V1. Back in the days of piston powered airliners, this was something that occurred from time to time. It still does occur today, but with extreme rarity. Under part 121, a departing aircraft must be capable of accelerating to V1, losing an engine, and then safely continue the take off with the remaining runway. This is all calculated based on the specific runway to be used, any upslope or downslope to that runway, runways surface conditions, terrain and obstacles (i.e. trees or cell towers) the current wind, temperature and barometric pressure, as well as the specific weight and balance state of the aircraft. (This is why you are asked to be in your assigned seat for take off and landing.)

All these parameters are calculated via a computer program by an airline dispatcher for each aircraft, every time it goes to take off. Ever wonder why the runways are so damn long in places like Dallas? Hot weather lowers engine performance. How about Denver? Higher altitude, hence lower atmospheric pressure, also lowers engine performance. Longer take off rolls are needed and expected.

The general accepted guidance these days is that if you haven't reached 80 knots yet, an abort will be initiated for pretty much anything. (This is considered a low speed abort.) For speeds above 80 knots but below V1, an abort will be initiated for critical things such as, an engine fire, an engine failure, lost of directional control or serious control malfunction. Once you've accelerated past V1, you will be going flying. If something goes wrong after that, you'll likely be coming right back around for an immediate and emergency landing.

The real bastard is when you're accelerating for take off and you're juuuuust about at V1. Lets say that's when the malfunction occurs. Keep in mind it takes a second or two, to process what the malfunction is and what it means. This brings us to that second question. What caused the abort to be made? If all we had to worry about was an engine failure the stay or go decision would be fairly easy. However, the systems on today's jets are far more complex than the regulations would have you believe. This means more caution and/or warning messages can be thrown in the crews faces.

Nearly all malfunctions, including engine failures, that occur at V1 or after, are best handled by taking the aircraft into the air, and either addressing it in flight (where you won't hit things like trees, buildings and mountains) and/or bringing the aircraft in for an immediate landing. High speed aborts are very dangerous. More people have been hurt/killed during high speed aborts than from crashes that occurred after the plane was airborne.

In fairness, I said "nearly" in the last paragraph because there are some malfunctions that do warrant a high speed abort. The trouble is, this must be a SPLIT SECOND decision made by the crew. The closer you are to V1, the more time critical the crew's reaction. Sound tough? You damn skippy! Some people might say it's better to always abort and stay on the ground. After all, it sounds safer and doesn't conjure up horror movie scenes of airliners falling out of the sky on a dark and stormy night. Let me give you an example of why this, as a general practice, is not a good idea.

We're on the runway and the take off roll is underway. The aircraft accelerates past 80 knots and continues to accelerate, all is normal. Just about at V1, there is a caution or warning indication. Some kind of BEEP or DING is heard and flashing yellow or red lights are seen. Lets say the crew pulls the power back and stamps on the brakes. Doesn't sound too bad, right? Now, let's say that warning was for a brake system malfunction.

To continue the take off would be a complete and total non-event. The aircraft would take off just fine and be fully controllable. Then, the aircraft could be landed back at the departure airport, on the longest runway available, or even landed at another airport with even longer runways. Perhaps after getting into the air and running a checklist or two, the brake system can be brought back on line, at least to some extent, facilitating a normal landing. The point is, there are several options available with this course of action.

Aborting the take off in this case, you are now tasked with trying decelerate an aircraft traveling at 150 MPH or more, on the remaining runway, with a compromised braking system. Since the regulations are really only considering an engine failure, the stopping distance calculations are assuming a fully functioning braking system. In this case, the aircraft will very likely be stopping well beyond that.

To argue both sides of the equation, lets say that after V1, the flight controls freeze. In this case, yes, it is better to abort the take off. You are past V1, however, without directional control of the aircraft, it won't fly very well. You will probably run off the end of the runway trying to get it airborne. But at least you will do it at 40 knots, rather than 140 knots.

I must say, I'm quite pleased that the passengers quoted in the article have an appreciation for the split second decision making that is required by a flight crew in such a scenario. It is true that there were no injuries or deaths. So, it's hard for the media to say this crew was in the wrong. The outcome was a positive one.

However, if the abort was made for something silly, then really, the actions of the crew were incorrect. If the warning was for something non critical, the crew should have continued the take off. By aborting the take off, the aircraft was damaged and the runway was closed until the aircraft could be removed. Worse yet, if during the investigation, the abort was determined to have been initiated
after V1 was reached, it would be very hard for the crew to talk their way out of disciplinary action by the company and the FAA.

So, we don't have enough information yet to tell if this crew really got it right or not. We shall just have to wait and see what other facts emerge. And, just in case you were wondering, I am indeed hoping they got it right.

A pilot's job might seem filled with repetition. However, any one of those 1000s and 1000s of flights could be very different from the others. Flight after flight, month after month, year after year, pilots can't let their guard down. This was brilliantly expressed by Deborah Hersman of the NTSB when she recently said, "You never know on which flight your career will be judged."