Blown Tire...to abort or continue prior to V1

[Hawkerflyer]

Hey all,
As per the discusion with the WestJst blown tire, I have been surprised as to the amount of people who would continue the take off phase prior to V1. To me thats crazy! Personally, Im stopping the aircraft! If you have a blown tire you are not likely to make your V1 let alone your Vr. Think of the other issues that could arise to this, damaged airframe, fire etc.
Lets get some thoughts on this and please keep it a healthy debat
Like I said, anything before V1 (decision speed) and im stopping the airplane.
Cheers

[bezerker]

Some previous discussion.

viewtopic.php?f=54&t=60491&hilit=balanced

[BTD]

Keep in mind that V1 as defined by the manufacturer, relates to the critical engine failure recognition speed, it does not factor in any other critical failures that could alter controlability of the aircraft, unless your company calculates the V1 speed differently based on its operations.

1.9.1 V Speeds

V1 = Critical engine failure recognition speed *

* This definition is not restrictive. An operator may adopt any other definition outlined in the aircraft flight manual (AFM) of TC type-approved aircraft as long as such definition does not compromise operational safety of the aircraft.

A consideration, therefore, is that a blown tire will change the braking capability of the aircraft and you are no longer operating within the accelerate stop distance calculations you had figured.

IE:

You may not stop before the end of the runway

You have rejected a take-off based on V1 speed, which only relates to engine failure.

I'm not saying you shouldn't reject, just that you may not stop due to degradation of braking capability.

Here is an excellent accident report for details about V1. It doesn't however, relate to blown tires.

http://www.tsb.gc.ca/eng/rapports-repor ... 5h0015.asp


BTD

[Darkwing Duck]

My thoughts would be stop the brute before V1, or if past V1 continue the TO, regardless of an engine failure or blown tire. If you have an engine failure, engine thrust is going to be retarded or reversed regardless. Would one not do the same with a blown tire, you cut the throttles, hence reducing the thrust, hence reducing the forward momentum, hence hopefully stopping prior to the end of the pavement. Is the V1 not based on max braking and reverse/nil thrust. Lost engines should not realy factor into this. My concern would be the asymetry now on the landing gear, causing a drift to the edge of the abyss.

I would think with a blown tire continuing the takeoff and coming back in for a landing would add extra stress to the gear and a potential for more blown tires and having the aircraft swerve off the rwy and into the shrubbery, causing more damage to the airframe, engines, pride.

Now I do not fly nor am I an engineer but from my experience with aircraft speeds on landing, rotation, and the like, keep er on the ground if you can. My $0.02 worth.

[BTD]

It is not about thrust setting, it is about braking capability of the aircraft.

Again, I am not saying to continue the take-off, only that you must prepare yourself for a bad situation.

Eg.

You have calculated your accelerate stop distance to be 6500 ft. Your ASDA is 7000 feet. If your V1 is 130 kts, and your tire blows at 125, at which point you reject the take-off, it is entirely possible that since you no longer have the braking capability that the manufacturer assumed when you did your calculations (due to the blown tire) you may have increased your stop distance by a margin larger than what you have remaining on the runway. In this case I'll pick 800 ft.

This now puts you 300 ft beyond the end of the runway and into the weeds.

[iflyforpie]

You may not have the braking capabilities, but you will have the added benefit of reverse thrust that isn't included in your initial calculation.

Don't forget that after you decide to take off, you also have to land with that damaged gear. Landing distances aren't as long as ASD distances, but the force of the landing is far harder on the gear and could result in even more damage and mayhem--especially if the aircraft decides to depart the runway sideways.

Also consider the effect the extra drag might have on a takeoff run; your accelerate-go distance might negatively affected as much as the accelerate-stop distance.

[AuxBatOn]

Personnal thing here. Anything wrong before 100 kts, I abort. Anything significant (Engine Failure, Fire, Flight Control Problems, Major Electrical Problem) after 100 kts but before abort speed, I abort, otherwise, I go flying. If I didn't have a hook to land with and a funky landing gear system, I'd include significant directionnal control problem in the significant events.

[Cougar]

Or, as a 30,000-hour test pilot I know would sum this up:

"Now, why would you want to bundle up all that trouble, and lift it off the ground with your ass attached??"

[BTD]

You may not have the braking capabilities, but you will have the added benefit of reverse thrust that isn't included in your initial calculation.

Agreed, but if that is the thought process, then V1 itself isn't as critical because you could abort 1 kt above V1 and in your mind believe that the extra reverse that wasn't included in the initial calculation will save you that extra distance. But it isn't likely too many people would argue in favour of that point.



Again, all I'm saying is that a reject below V1 in circumstances different from an engine failure doesn't guarantee you will stop on the runway. However, many people believe this is the case.

If you are heavy and near the limits of that runway, a blown tire could put you over the available stopping distance remaining, in which case prepare for an exciting ride. In my opinion though, this is still a better option than a wheel well fire that progresses to something more disastrous.

http://tsb.gc.ca/eng/rapports-reports/a ... 087.asp#a3

[Pratt]

Our take off briefing goes something like this," Any problem affecting safety before V1 I will reject, engine failure after V1 I will call.....................

That phrase "Any problem" covers a lot of areas.

In my opinion it is better to keep a problem on the ground rather than taking a known or unknown problem into the air.

For the arguement of if it is 1 or 2 knots after V1, by the time V1 is called, the malfunction called out, making the decision to reject, you are definitely more than the 1 or 2 knots above V1 by the time it is initiated.

[Hawkerflyer]

But is Vr even going to be reachable? I can tell you I wouldn't wait for it cause I am a stoppin!

[AuxBatOn]

That's why you do your homework before the flight. Normally, if you are before abort speed, you have enough runway to stop in time. From above speed and beyong, you have to go airborne if you have an engine failure.

I think it's safe to say that if you are below abort speed and you have a blown tire, you will be able to stop in time, even with the added distance due to the fact that 1 side isn't braking, since you will have access to the thrust reversers.

Also, there is the pilot thing that must kick in.

[Pratt X 3]

Some fuel for the fire: http://www.smartcockpit.com/data/pdfs/p ... rev_03.pdf
http://www.smartcockpit.com/pdf/plane/b ... ctor/0027/

[Steve Baker]

It really isn’t our place to second guess the actions of the crew but, to inject some facts into the discussion, I quote from the 737ng QRH manoeuvres section. The quote is giving guidelines on the reject decision. It is important to note that a flat tire at high speed can cause heavy vibration and some yaw. It is possible to miss-diagnose and can also convince a crew that the aircraft is unable to fly.

Clearly Boeing doesn’t think a tire failure in and of itself justifies a rejection above 80 kts.

In this specific case, the crew did a fine job, the aircraft was stopped on the runway with no more damage done than would be had if they had carried on with the take-off and returned for a landing. I just wanted to counter those that seem to think a tire failure below V1 but, in the high speed regime, calls for an immediate reject.

Prior to 80 knots, the takeoff should be rejected for any of the following:
• activation of the master caution system
• system failure(s)
• unusual noise or vibration
• tire failure
• abnormally slow acceleration
• takeoff configuration warning
• fire or fire warning
• engine failure
• predictive windshear warning
• if a side window opens
• if the airplane is unsafe or unable to fly.
Above 80 knots and prior to V1, the takeoff should be rejected for any of
the following:
• fire or fire warning
• engine failure
• predictive windshear warning
• if the airplane is unsafe or unable to fly.

[arctic navigator]

This now puts you 300 ft beyond the end of the runway and into the weeds.

Who cares if you go off the end, that's what insurance is for. A little bent metal and a bruised ego is way easier to deal with than a fireball. Your passengers, and likely yourself as well, will walk away with nothing worse than some cuts and bruises if you go off the end at 50-60kts slowing down. What's the outcome going to be if you take it to the air, if you even can get there? If all goes well the aircraft won't have a scratch other than the damage from the blowout, but that's one big if...

[Bede]

If you try to reject just short of V1 with a blown tire in any airplane with any size to it, there is a good chance you will blow the other tire. Than you end up with a directional control problem as well. I read an article in the FSF publication a while back that for most circumstances it is better to continue a take off (especially in a balanced field condition) than attempt a reject. Sorry don't have a link. To each their own I guess.

[BTD]

This now puts you 300 ft beyond the end of the runway and into the weeds.

Who cares if you go off the end, that's what insurance is for. A little bent metal and a bruised ego is way easier to deal with than a fireball. Your passengers, and likely yourself as well, will walk away with nothing worse than some cuts and bruises if you go off the end at 50-60kts slowing down. What's the outcome going to be if you take it to the air, if you even can get there? If all goes well the aircraft won't have a scratch other than the damage from the blowout, but that's one big if...

This was my point. If you read all my posts.

I'm simply trying to highlight what V1 actually is. There are many people out there that think "if I reject a take-off before V1 I will get it stopped." This is not the case. If you reject a take-off due to an engine failure the numbers say you should be able to stop it. If it is for ANY other reason there is no guarantee. You may not get it stopped. Especially if you are heavy and near the limit of the runway. A tire failure is a situation that will seriously degrade stopping distance and directional control. Expect more blown tires, and possibly a fire, leaking fuel etc.

But I agree going off the runway at a slow speed is better than having a catastrophic failure in flight.

Here is what Airbus Says

http://www.airbus.com/store/mm_reposito ... -SEQ04.pdf

Tire burst in the V1 minus 20 kt to V1 range: Unless debris from the tires have caused serious engine malfunctions, it is far better to get airborne, reduce the fuel load, or proceed for an overweight landing, and land with a full runway length available

http://www.bluecoat.org/reports/TOSTA-appendix-4.pdf

It won't let me cut and paste from the PDF, but at the bottom of Page 6 from this last link it gives an example of a Convair 990 that rejected prior to V1 with a tire failure, that overran the runway.

The report also states that between 1964 through 1976 171 RTOs that caused damage or death occurred and of those 149 involved wheels, tires, and brakes, of which 124 were a direct result of tire failure. Some were initiated before V1, some at, and some after V1.

Excellent report from the link above.

BTD

[Raybanman]

Who cares if you go off the end, that's what insurance is for. A little bent metal and a bruised ego is way easier to deal with than a fireball. Your passengers, and likely yourself as well, will walk away with nothing worse than some cuts and bruises if you go off the end at 50-60kts slowing down. What's the outcome going to be if you take it to the air, if you even can get there? If all goes well the aircraft won't have a scratch other than the damage from the blowout, but that's one big if...

So you would rather go off the end at 60kts, go through the lead in lights and ILS equipment, damage the aircraft and have to evacuate with a possible fire because of damage to the aircraft rather than become airborne, come back to the airport on the longest runway available, put the aircraft down on the pavement and deplane?

I doubt a blown tire will prevent you from accelerating to V1/Vr. But it sure will decrease how well you brake. Less rubber = less grip, and now try stopping from 125 kts with 3000' of runway left. Come back around to land and you have 12000' of runway to stop.

[Liquid Charlie]

"Now, why would you want to bundle up all that trouble, and lift it off the ground with your ass attached??"

Well I tend to disagree with this statement since a lot of the time you are better off dealing with situations in the air -- but I will clarify a little -- this is from a transport catagory airplane point of view -- since I have seen guys reject a takeoff in a 2 otter with an engine failure and be 50 feet in the air.

Given the choice in a "high speed" reject situation there are only a couple of items I won't proceed with -- blown tire is not one of them. and how the hell can you confirm that it is a blown tire anyway -- first you usually hear of that is someone reporting debris on the runway.

We all know the famous one of the DC10 in YVR --

Me personally think the question of when you reject a landing is more critical - deployment of reverse is a hard rule so anytime before that or do you just hang on and go off the end or try and steer around that truck and come to rest in the mud or do you launch and hope nothing goes wrong --

[Cannonballer]

This may have been covered in this post already if so disregard. If you have a blown tire you must also consider what other damage has been done. Has a retread come off and damaged your hydrolics... will your flaps or ailerons be effective. Also have the flying peices of rubber damaged other control surfaces physically ... personally i would abort and deal with the braking issues rather than fly away with a broken and possibly uncontrolable airplane.

[BTD]

We all know the famous one of the DC10 in YVR --

In this instance the reject was initiated beyond V1 and the captain believed it was a bomb.

However, my link above gives examples of rejects below V1 due to tire problems and not getting it stopped.


The Concorde accident is an illustration of the opposite effect.

The real point is that if you reject due to a failed tire you should realize that your accelerate stop distance no longer applies and you have no idea how long it will take to stop.

You may choose to make that decision anyway, based on your experience on type, total experience nature of the tire burst etc. But don't believe for a second you are guaranteed to stop because you rejected before V1.

BTD

[Liquid Charlie]

In this instance the reject was initiated beyond V1 and the captain believed it was a bomb.

Most are aware of the situation and circumstances around that classic cockup -- certainly training has now tried to address the situation caused by that incident.

No high speed reject is going to guarantee you stop in the advertised (computed) distance and contrary to what many think I will go out on a limb and state that any high speed reject will cause damage to an airplane at the very least tires will blow -- hopefully after you stop but suffice to say that aircraft will not go flying again that day -- break units will need replacing and likely tires will blow their fuses and go flat -

Below 80kts it's a non issue - after that if it's not clear what the thump or bang was and the aircraft is performing with no control or acceleration issues you are likely better off dealing with it in the air. V1 or above -- better go flying -- that's what we are trained to do and if you question that maybe you should sit down and rethink your career options - V1 is no time to start second guessing our muscle memory.

Now I'm going to get a good Cuban cigar and a beer and enjoy the sunshine

[pelmet]

Have you changed your mind yet HawkerFlyer? I hope so because I'm going and those who decide to stay behind when at high speed but still below V1 have made a dangerous decision.

[BTD]

I havn't heard of an airplane yet with a blown tire indicator or caution light. Some have temperature indication but it may not be accurate or even trigger until well after the event has occured. I wish you good luck sorting out the issue you have on your hands while your trying to make that decision to reject or not. I stand by the proven plan, before V1 we STOP, after V1 we GO.

That's just it, that plan is not proven. Deaths have occured as a result and accident investigators have opinions on the matter after studying numerous accidents due to that decision.

However, even if stopping is the right decision, you might still go off the end, wrecking the airplane with possible loss of life.

http://www.bluecoat.org/reports/TOSTA-appendix-4.pdf

Page 33 Appendix C

Tires, Wheels, and Brakes

To further compound the problem, an FAA study determined that 87% of rejected takeoffs were caused by tire, wheel, and brake failures. Douglas estimated "the figure at around 50%. Yet, critically, these components are required to be 100% effective to achieve the scheduled stopping distance.

Page 19 - Here is what the FAA and the AAIB have to say.

The date indicated the pilots often incorrectly interpret the cues accompanying noncritical evens (such as simple tire failure) as events threatening the safety of the flight; as a result, the pilots incorrectly decide to perform an RTO. The safety Board believes that presenting flight crew members with realistic cues accompanying noncritical events will better prepare them to recognize these events should they be encountered during takeoff.

[florch]

At high speed I reject if it:

dings (fire bell)
sings (windshear) OR
swings (engine failure)

Otherwise I'm going flying. I'm pretty good at flying circuits.