High Speed Aborts

[LockheedFix]

In order to not derail a classic thread, but continue a rather good discussion, I'll pose this question here.

What is so "dangerous" about a high speed abort on a long runway? I hear people brief over and over that they would rather continue the takeoff for "x" than do a high speed abort.

Here is my take on it (keep in mind, all my experience is in the C-130 and we routinely take off and land with about 8,000' more than we actually need.) Say you're taking off full length on Runway 25 at LRF. You have 12,000' of runway in front of you. Say you get an abort call just before rotating, we'll call it 110 KIAS. Definitely a high speed abort. But you also have about 9,000' feet of runway in front of you and you are also at an airspeed that would be just a little higher than your touchdown speed. So you are in basically the same situation as if you had landed fast, 2,000' long.

I have seen numerous people brief avoiding the dreaded high speed abort for a minor malfunction as if their brakes will catch fire and kill everyone on board, and most of those same people would have no qualms about landing 8 KIAS fast with 9,000' remaining. So what's the difference." Discuss.

(DISCLAIMER: I did not reference the -1-1 for any of the hypothetical TOLD in this scenario.)

[Guest Hueypilot812]

I'll repost my original statement:

Yea, but high speed aborts are exceedingly more dangerous than a go-around

That depends. I'm currently working on something concerning the decision to abort or go around. There is credible evidence that suggests our innate desire to get airborne again kills a lot of people. For example, Cessna Citation lands mid-field on a 4,000 foot long runway approximately 10 knots fast, realizes there's not enough runway to stop, pushes the throttles up to try and go around, and blasts through the fence and a house at 120 knots, killing everyone on the airplane and the occupants of the home. Had he aborted, he would have likely gone through the fence, but at a much slower speed.

This is a good read:

When Go-Around is Impossible

From the article above:

The fundamental question is when and where on the runway is the point-of-no-return for a go-around reached. The aircraft may or may not be able to stop on the remaining runway.

However, if it is slowed below the minimum safe go-around speed, there will not be enough runway remaining for it to become safely airborne either. Therefore, the crew should accept a runway overrun as a lesser evil.

[Techsan]

Boeing Rejected Takeoff Studies

Read the attached article from Flight Safety magazine. It was written by a former KC-10 guy and has some good arguments against high-speed aborts. BTW, high-speed anything and C-130 doesn't jive!

Abortarticle_Hummel.doc

[matmacwc]

Try it in a T-38...

[EvilEagle]

Try it in a T-38...

Agreed! I think it has a lot to do with what you are flying. The Eagle is the biggest thing I've ever flown, so having said that I'm on the take-it-airborne side of the fence. In the fighter world, the brakes (and all the other safety stuff for that matter) are an afterthought to the rest of the killing bad guys stuff - at least it seems that way. The "anti-skid" braking is a joke, the system is known for catching on fire and blowing tires. I've had a brake stack catch on fire during a long taxi-back & I wasn't riding the brakes excessively. For non-catastrophic emergencies (basically anything other than dual engine problems or pitch ratio and pitch cas), I will take the jet airborne instead of high-speed abort.

Our -1 requires 8k' of runway. Many many times it's easy to land with much less runway available than that if you are light-weight. The ROT most of the contract guys at TY brief is 1k# of gas for every 1k' of runway. I know lots of IPs that won't brief that to students though - they don't think it's conservative enough. On a normal training configuration, we'll be taking off with around 20k# of gas. Rotation (assuming AB takeoff) will be no further down the runway than 2300'. Lets assume rotation is close to final approach speed (it's actually a little slower for AB takeoffs) - you have just used up 2300'-2500' of runway, you are accelerating extremely fast, the aircraft is in an unstable position for applying wheel brakes (aerobraking is your best bet above 100k) and you have about 15k# more gas than you normally have during landing. 15k doesn't sound like much to most of the heavy drivers, but when your airplane only weighs 50k or so full & normally around 35-40k# when you are landing, 15k# makes a big difference.

Obviously that decision is easier for non-thrust limited airframes. Unless it's 130 degrees, and we're in Denver the refusal speed (I think it's called that) is 0 for us. We can shut a motor off before taking the runway and get airborne. Not bragging here, just relaying state of mind that thrust (other than previously mentioned situations) is not usually a problem worried about.

I've done both: high speed abort and take a bad jet airborne. Different jets, different days, different decisions but I stand by both of them. Neither was fun. The high speed abort ended in a departure end cable engagement (if it hadn't been for the cable, I would've been in the grass I'm guessing) and taking a bad jet airborne is always fun. LockheedFix - not trying to scoff what you are saying, just throwing my unsolicited .02 in there.

[HerkDerka]

I have to agree with EvilEagle. It definitely depends on what you're flying.

In the Herk he have the luxury of going to idle with the four speed brakes of freedom, reverse, and a big time brake system. High speed aborts aren't the same danger to us that they are to an aircraft that only uses brakes to slow down.

I think the big reason people brief against a high speed abort is the brakes. The brakes are already warm from taxiing out. If you did a static takeoff, there's some more heat. Then add that to the energy absorbed during a high speed abort where you're using max braking. It's a likely time for a brake fire.

But like the man said above, different situations and different actions.

HD

[LockheedFix]

LockheedFix - not trying to scoff what you are saying, just throwing my unsolicited .02 in there.

No offense taken. I was just starting the conversation to see different points of view.

[Flare]

Concur with all Evil said for the Viper as well. About the only thing we have going for us is the hook. The single-engine thing also takes some of the decisions out of your hand as well....

The high speed abort is also a big risk when you blow a tire in an airplane that only has 3 to begin with too. If you want to know why alot of us are so "go" inclined, read the SIB from the T-38 crash at Randolph on 20 Mar 03.

[LockheedFix]

I have to agree with EvilEagle. It definitely depends on what you're flying.

In the Herk he have the luxury of going to idle with the four speed brakes of freedom, reverse, and a big time brake system. High speed aborts aren't the same danger to us that they are to an aircraft that only uses brakes to slow down.

I think the big reason people brief against a high speed abort is the brakes. The brakes are already warm from taxiing out. If you did a static takeoff, there's some more heat. Then add that to the energy absorbed during a high speed abort where you're using max braking. It's a likely time for a brake fire.

But like the man said above, different situations and different actions.

HD

I agree with what you are saying and have heard all the reasons that you mentioned and how they can lead to hot brakes. It is a little different in the J however, since we can put all four all the way to reverse in LSGI. Couple that with oil cooler augmentation, and you can easily taxi all the way to the runway and never touch the brakes except for checking them.

Now take what you said and apply that to the discussion in the 'Deid thread about the aborted T&G. You've just landed after an approach, your brakes should be nice and cool. Now assuming you didn't float the landing, even after resetting the flaps and trim you should have at least 6,000' feet left even after pushing the throttles back toward takeoff. I just find it funny that people were talking about a Q-3 for aborting in this situation.

[TreeA10]

"High Speed" are two words that do not belong in the A-10 vernacular. However, on the big jet side, the FAA mandates the use of auto-brakes. So, for something like a 757/767, if you reject a takeoff above 80 knots, you get max autobrakes. At higher gross weights, you are at least going to melt the fuse plugs. The rule we use is if anything affects the ability of the jet to safely fly and you are 80 knots or greater, abort. Otherwise, press with the takeoff and sort it out once airborne.

[slacker]

I just find it funny that people were talking about a Q-3 for aborting in this situation.

I think the Q-3 talk was about the total lack of SA, coupled with the high speed abort. It was a crappy decision to abort for a light that has/was always been illuminated and shows a total lack of airmanship.

In the J, you can go or stop- because of its awesomeness.

[HerkDerka]

It is a little different in the J however, since we can put all four all the way to reverse in LSGI. Couple that with oil cooler augmentation, and you can easily taxi all the way to the runway and never touch the brakes except for checking them.

Interesting, I didn't know that about the J. So with the oil cooler augmentation, do you see any rise at all in the oil temps when reversing on the ground or is it just a decreased amount?

HD

[slacker]

Interesting, I didn't know that about the J. So with the oil cooler augmentation, do you see any rise at all in the oil temps when reversing on the ground or is it just a decreased amount?

HD

Nothing out of the normal operating temps.

[PirateAF]

It's the same story for the 17 as the 130...we are usually reject oriented. Our brakes were made to bring a 500K aircraft to a stop on an ALZ, so it's only on heavyweight takeoffs where we go split markers at the 130s and rotate at 145 or so. We can usually safely reject heavyweight with out worrying about blown fuse plugs up to the 120s.

I've got a pretty in-depth C17 rejected takeoff brief if anyone's interested (PM).

[Guest Form 8]

I just find it funny that people were talking about a Q-3 for aborting in this situation.

You can be Q-3'd for anything at anytime. I don't know how it is in the Herk would but in the -135 world unless briefed otherwise the A-Code is the abort authority and has final say. That's why I asked the question to begin with. A high speed abort in a -135 without the new carbon brakes is a big deal. Especially when you're above 300K gross weight. It's a good way to practice your egressing since the brakes are most likely on fire.

Edited April 27, 2009 by Form 8

[Guest Detzel]

Try it in a T-38...

With one motor stuck in blower.

[pawnman]

I'd rather take the B-1 flying than high-speed abort. Alot of it has to due with weight for us...we're typically taking off at a fatter weight than our ideal landing weight, so there's more mass, and therefore, more momentum for the brakes to overcome, even at the same speed as a long landing.

[TacAirCoug]

I think the Q-3 talk was about the total lack of SA, coupled with the high speed abort. It was a crappy decision to abort for a light that has/was always been illuminated and shows a total lack of airmanship.

To go one step further...

One thing we all have hammered into our skulls from day one of pilot training is to analyze the situation BEFORE you take action. I have no direct knowledge of the incident that generated this discussion, so I won't scream bloody murder for a Q-3. However, it sounds like she just reacted without thinking. First, not noticing the light earlier - strike 1. Second, not knowing that the light is always illuminated - strike 2. Third, opting to high-speed abort on a touch-and-go for a bus off light? Strike 3. Are you sure the SA low light wasn't illuminated as well?

Regardless of whether you can high-speed abort in a Herk, often it just doesn't make sense, and sometimes it's just plain dangerous. She clearly didn't know what the problem was, so what if that light had been a prop low oil light and she reacted the same way? 9 times out of 10, the prop is fine, but what about that one time where it dumps all its fluid and doesn't change pitch when you rip the throttles back to idle, or worse all the way to ground idle, at high speed? You think that 9000' of runway remaining is going to do you any good now?

There are a lot of problems in the Herk that you don't need to abort for, and some that might end up with you pissing in a cup if you do.

[Guest Caddis]

Interesting, I didn't know that about the J. So with the oil cooler augmentation, do you see any rise at all in the oil temps when reversing on the ground or is it just a decreased amount?

HD

Augmentation in the H model also. I feel your E model hot brake pains and it is one of the many reasons I do not miss my E model days.

[Butters]

One thing we all have hammered into our skulls from day one of pilot training is to analyze the situation BEFORE you take action.

Yes, you need to know what's happening before you do something that may make the situation worse. All aircraft are different, but remember... Some people have flow different airframes and in a emergency you can revert to another aircraft in an emergency. This can have fatal consequences in a time critical emergency.

Remember the Lear 60 with the Blink 182 drummer? High speed aboard that went wrong and people dies. That aircraft could have become airborne with no problems, but stopping with a blown tire at high speeds is not easy.

The discussion on Go-Around vs. aborting are not really the same thing. They are more geared towards aborts after go speed. Yes, it is better to hit the fence at slow speed vs. high speed, but a go around should happen fast if you screw up and land long. Problems arise when decisions are excessively delayed or made to quickly without regards for the outcome. That is why you should pre-brief decision points.

You don't Q-3 someone to be a dick, you pass out Q-3s to show someone needs extra training. In this case she needs extra training in multiple areas.

[Guest Pony]

The decision to abort should have already been thought about long before you even take the runway. If you think you are going to critically analyze the situation at 150 kts, best of luck to you. This caveman can't do it reliably. You should have your personal criteria ready to go anytime you take the runway. In the airlines, most of that decision is already made for you. As nazi as the AF is, I have been surprised at the lack of guidance at times. Realize that heavy aircraft are made to reject at V1 only once. You will more than likely fry the the brakes and tires, but at least you will stop.

[matmacwc]

Dont' know what V1 is personally, but in the F-16 it was gear in the well for most problems. In the T-38, it is 1 number, go or stop, makes the decision easy for a single seat guy.

[RangerMateo]

If you did a static takeoff, there's some more heat.

Is that actually a consideration in your braking charts? Not trying to be a smartass I just am curious if there's some physics/thermo concept I'm missing here because it doesn't seem like a static TO should add anything more than a negligible amount of energy into the brakes as long as you aren't creeping or dragging the pads for an extended period of time while releasing brakes.

[Guest Vettepilot]

Is that actually a consideration in your braking charts? Not trying to be a smartass I just am curious if there's some physics/thermo concept I'm missing here because it doesn't seem like a static TO should add anything more than a negligible amount of energy into the brakes as long as you aren't creeping or dragging the pads for an extended period of time while releasing brakes.

agreed, the heat comes from friction and if you are static then there shouldnt be any, i cant find anything in my -1-1 that says anything about brake heat from statics but if there is something that causes it and it just isnt written i'd like to know

[Herk Driver]

Regardless of whether you can high-speed abort in a Herk, often it just doesn't make sense, and sometimes it's just plain dangerous. She clearly didn't know what the problem was, so what if that light had been a prop low oil light and she reacted the same way? 9 times out of 10, the prop is fine, but what about that one time where it dumps all its fluid and doesn't change pitch when you rip the throttles back to idle, or worse all the way to ground idle, at high speed? You think that 9000' of runway remaining is going to do you any good now?

Exactly what I was thinking. 9K in front of you and only a hundred feet (or way less) to the left or right. You can end up in the infield pretty fast. A lot of -130 T & G's, it doesn't take very long if any amount of time to already be beyond Go speed. You just have to get the power pushed back in. As someone else already said, this should have been talked about in the pre-brief. Most -130 guys that I know normally brief not to use the term reject for a T & G anyway, but if you notice something out of the ordinary to bring it to the AC's attention and he will make the call whether you stop or go airborne (obviously based on speed, throttle position, runway remaining, etc).

Edited April 30, 2009 by Herk Driver