feb 01 westjet rejects t/o..

[oldncold]

according to the 'Aviation Herald west jet 737crew in Vancouver rejected. a take off due to blown tires. good job. and that training sure what makes Canadian airlines among thee safest.

[Nark]

Unlike the Qataris where the pilots cannot be trusted to make the decision...

http://thepointsguy.com/2015/12/aborted ... om-the-us/

[iflyforpie]

Unlike the Qataris where the pilots cannot be trusted to make the decision...

http://thepointsguy.com/2015/12/aborted ... om-the-us/

Insh'Autobrake?

[pelmet]

C-GVWA, a Boeing B737-800 operated by WestJet as flight WJA1876, was departing Vancouver
Intl, BC (CYVR) for Kahului Intl, HI (PHOG) with 157 passengers and 6 crew members on board.
During the takeoff roll on Runway 08R, a left main tire blew at about 120 knots IAS; shortly
thereafter, the second left main tire blew. The takeoff was rejected and an emergency was
declared with ATC. The aircraft remained on the runway and came to a stop about 7 200 feet down
the 11 500 foot runway. ARFF attended the aircraft; there was no fire. Passengers and baggage
were deplaned, requiring about 2 hours. The disabled aircraft was defueled to enable the wheel
assemblies to be replaced. Since the height of the aircraft in its current state was lower than
normal, non-standard jacking equipment was required. The runway was closed for about 7 hours
and 40 minutes. Preliminary inspections did not identify further damage to the aircraft or the
runway.

Seemed to work out well. It would be interesting to see what Boeing recommends as reasons for rejecting a takeoff below and above 80 knots on the NG.

[GRK2]

Below and above 80 knots...Boeing: (Simple really)

Below 80: Stop for any caution or warning (EICAS or Master)

Above 80:
1) Engine failure recognized by 2 parameters
2) Engine fire (EICAs and Master Warning)
3) Take Off Config Warning(s)
4) Blocked Runway
5) If, in the consideration of the Crew, the aircraft will not fly.

That's it...there's nothing about tires in the FCTM, 120 knots is pretty quick, but I don't know what parameters WS uses for performance and what the V1/VR/V2 numbers would be. On the heavier jets, it's sometimes a really big number (over 170 knots) with not a great deal of Runway left and a tire burst would be a "continue" call if it was close to V1. Better to take the jet airborne, sort it out and come back or continue, than to reject at a high speed and end up with more than a blown tire.

[crazyaviator]

wrong posting

[crazyaviator]

!

[GRK2]

Wrong post...are you saying that my post is in the wrong place? If you look above, someone wondered what Boeing recommended about rejecting the NG above and below 80 knots, which is the subject of my post...if I'm in the wrong spot, tell me where I should put the post.

Cheers,
GRK2

[Donald]

2 on one side could generate significant yaw, accompanied by the initial bang.

Crew may have initially mis-identified as an engine failure, or else was concerned by the directional control available and had lots of runway in front of them.

[fish4life]

I doubt with 2 blown tires you would be able to keep accelerating at a satisfactory pace to get airborne.

[Rockie]

There are no hard and fast procedures or recommendations like there are with V1. There is usually only the statement that if it happens at high speed it's considered better to take it airborne, lighten the airplane up and land with the whole runway available for stopping given the reduced braking effectiveness.

Stopping from high speed with blown tires is an iffy proposition and will most likely result in the remainder of the tires going as well causing a total loss of braking. Having said that it worked out well for this crew and they seem to have stopped in plenty of time, so it's hard to argue with success.

[crazyaviator]

Wrong post...are you saying that my post is in the wrong place? If you look above, someone wondered what Boeing recommended about rejecting the NG above and below 80 knots, which is the subject of my post...if I'm in the wrong spot, tell me where I should put the post.

i posted something in the wrong thread then deleted it nothing to do with anyone else

[pelmet]

Below and above 80 knots...Boeing: (Simple really)

Below 80: Stop for any caution or warning (EICAS or Master)

Above 80:
1) Engine failure recognized by 2 parameters
2) Engine fire (EICAs and Master Warning)
3) Take Off Config Warning(s)
4) Blocked Runway
5) If, in the consideration of the Crew, the aircraft will not fly.

That's it...there's nothing about tires in the FCTM, 120 knots is pretty quick, but I don't know what parameters WS uses for performance and what the V1/VR/V2 numbers would be. On the heavier jets, it's sometimes a really big number (over 170 knots) with not a great deal of Runway left and a tire burst would be a "continue" call if it was close to V1. Better to take the jet airborne, sort it out and come back or continue, than to reject at a high speed and end up with more than a blown tire.

Thanks,

Looking at other Boeing manuals, I see...

Prior to 80 knots, the takeoff should be rejected for any of the following:
• activation of the master caution system
• system failure
• unusual noise or vibration
• tire failure
• abnormally slow acceleration
• takeoff configuration warning
• fire or fire warning
• engine failure
• predictive windshear warning (as installed)
• 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 (as installed)
• if the airplane is unsafe or unable to fly

One should be cautious about rejecting at 120 knots(ie.high speed) with a tire failure. Perhaps this crew was cautious and well thought out and that was the reason for their success. Loud bang with yaw thought to be an engine failure leading to an RTO? That could happen.

[Illya Kuryakin]

You guys have taken several days to analyze something the crew had about two seconds to digest. They rejected. Get over it.
Illya

[#37]

Amen Ilya.
There is no "blown tire" light, but the accompanying sensations can be alarming.
There is also the simple issue of damage caused by tires , particularly at high speeds. Think Concord and others. A reject prior V1 should be able to be safely accomplished or the numbers mean nothing. Getting airborne with unknown issues is a brave endeavor.

[GRK2]

Ilya, and #37...

Someone asked a question, he got answers, nothing to "get over". No one challenged the result that the WS crew got from their reject. Just a few cautions added from Boeing and experience. Cant argue with either!

Cheers,
GRK2

PS: Most know about the Concord accident, what "others" are you speaking of?

[Donald]

A reject prior V1 should be able to be safely accomplished or the numbers mean nothing.

Do the "numbers" account for the reduced braking effectiveness after the loss of both mains?

Again, not questioning this crew as you can't argue the outcome. This is purely for discussion.

So if you reject within 5kts of V1 of a perfectly balanced takeoff, due to tire failure, will you have enough runway to stop?

[pelmet]

You guys have taken several days to analyze something the crew had about two seconds to digest. They rejected. Get over it.
Illya

Can't comment on what happened in YVR but, in general.....many days, weeks, months, years are available to make the decision on takeoff for a tire failure that is actually recognizable as a tire failure. It is being aware of what the manufacturer states as reasons to do an RTO(ie. tire failure below 80 knots).

A reject prior V1 should be able to be safely accomplished or the numbers mean nothing. Getting airborne with unknown issues is a brave endeavor.

Actually, your general theory is quite wrong. The reject prior to V1 is based on certain tested parameters, that include an engine failure just prior to V1. No testing is done and no performance numbers are provided for a tire failure scenario. The numbers are provided for all tires operational.

This is why the FAA Pilot Guide to Takeoff safety, a quite interesting read says...

"Rejecting a takeoff from high speeds with a failed tire is a much riskier proposition, especially if the weight is near the Field Limit Weight. The chances of an overrun are increased simply due to the loss of braking force from one wheel. If additional tires should fail during the stop attempt, the available braking force is even further reduced. In this case, it is generally better to continue the takeoff, as can be seen in Figure 17. The subsequent landing may take advantage of a lower weight and speed if it is possible to dump fuel. Also, the crew will be better prepared for possible vibration and/or control problems. Most important, however, is the fact that the entire runway will be available for the stop maneuver instead of perhaps, as little as 40% of it.

As can be seen from this discussion, it is not a straightforward issue to define when a takeoff should be continued or rejected after a suspected tire failure. It is fairly obvious however, that an RTO initiated at high speed with a suspected tire failure is not a preferred situation. McDonnell Douglas Corporation, in an All Operator Letter 4, has addressed this dilemma by recommending a policy of not rejecting a takeoff for a suspected tire failure at speeds above V1−20 knots. The operators of other model aircraft should contact the manufacturer for specific recommendations regarding tire failures."

https://www.faa.gov/other_visit/aviatio ... safety.pdf

As you may have noticed, it did say "... if the weight is near the Field Limit Weight". That may not have been the case with the incident above and the pilots may have been well aware of this and therefore were well aware of their large margins and acted accordingly. However, the information I pasted is still extremely relevant. That is the reason that Boeing only includes a very few very select, absolutely critical items for an abort above 80 knots but still below V1.

I doubt with 2 blown tires you would be able to keep accelerating at a satisfactory pace to get airborne.

Shouldn't be a problem actually. Here is a video of a heavy 767 with a tire failure at high speed. It appears to be a dry runway with a twin engine aircraft so V1 is likely close to Vr. Therefore I would guess that the failure was below V1...

https://www.youtube.com/watch?v=uxi602JQacU

[co-joe]

pelmet are you saying V1 was 140? Just curious what it was.

What would cause 2 tires on the same gear to blow? QAR will tell if it was a pilot input right?

[Rockie]

So if you reject within 5kts of V1 of a perfectly balanced takeoff, due to tire failure, will you have enough runway to stop?

No you won't. V1 in a balanced field scenario is based on maximum braking, that's pedals to the floor with operative antiskid and all brakes working. In a balanced field reject just prior to V1 with a blown tire you're going off the end.