BEEF SUPREME
Well-Known Member
I almost deleted my post since I broke my rule about speculation in regards to a form of aviation I know nothing about.
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Blue Angels crash in Nashville
- Thread starter Soku39
- Start date
I almost deleted my post since I broke my rule about speculation in regards to a form of aviation I know nothing about.
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Lawman
Well-Known Member
Why should you feel bad.
CNN does it all the time.
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BEEF SUPREME
Well-Known Member
I'm looking at this the wrong way. I should stop working so hard and speculate full time on CNN...
Make mad bank yo.
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///AMG
Well-Known Member
The parachutes packed into newer seats (NACES, ACES II) are quasi-"steerable", though not in the sense of a sport parachute. Low altitude/on-deck ejection doesn't give you a whole lot of altitude to drift away however. If you eject on an aborted takeoff (as in Mike's example), you aren't going to get much higher than a few hundred feet AGL.
It's too bad Indeed. In the end, his accident was determined to be pilot error for untimely execution of abort procedures following the decision to abort, which eliminated his ability to catch the 2550' BAK-12 a-gear and the non-deployment of the SAFE BAR web barrier which would've prevented his jet from going beyond the overrun.
///AMG
Well-Known Member
Takeoff abort is sketchy in any fighter aircraft, much moreso in the Viper. It doesn't have a really good track record of actually catching arresting gear due to geometry, and the brakes aren't that great. If you blow a tire, you are really off to the races so to speak. Couple that with really high acceleration (and inertia and all that), a decently high takeoff speed, and a general single engine mindset that is more willing to high speed abort for a serious engine problem when compared to two engined aircraft that can generally take a bad motor airborne and then troubleshoot from the relative safety of the air. In the F-16, if your engine is f'ed on rotation, you are either taking your chances at putting it back down for a high speed abort, or ejecting a few seconds later airborne. There is some serious judgement involved in making that decision and getting the best outcome.
Some interesting things that came out of that accident, in addition to what I noted above regarding the arresting gear maintenance and what was available. That day, he had an 8,000 ft avail runway due to the A-gear maintenance going on. There was some confusion as to the SAFE BAR departure end barrier, as it was believed by Wing pilots to be only for use or compatible with the JASDF fighters based at the field. There was concern regarding compatibility with the F-16, with regards to whether or not pilot entrapment in the cockpit could result from being fouled in the barrier after using it. Hence, many of the pilots didn't even know it was an available or viable option, and in flight crew information files regarding airfield ops during the runway maintenance, only the 2550' point BAK-12 was mentioned as being an available long field A-gear; there was no mention of the SAFE BAR being available, even though it was present out-of-battery, and merely needed to be activated by tower, on request. Hence, pilots believed there was only one viable long-gield A-gear, when in fact there were really two available.
With a 36,000 lb aircraft that day, 8000' runway, 162 kt dry V1, 179 kt T/O at 2500' distance, there should've been ample runway for an abort. Calc'd abort was 15 seconds after brake release with a max speed of 168 kts attained and about 3000' runway used. He announced his abort in a routine manner, but over the interflight VHF, rather than over tower UHF, so tower never heard any abort radio call. At this point, he had about 5000' remaining runway, and 2500' from the BAK-12. Nozzle was seen to be full open, speed brakes open, but the stabs did not appear to be in the full up position, nor was max wheel braking being applied, nor was the tailhook initially down. The tailhook was not extended until about 1800' from the end of the runway, or about 700' past the BAK-12. There had been no comms from the pilot to the tower during the entire abort, and about 1500' from the runway end, the JASDF tower controller asked the on-duty SOF whether he should activate the SAFE BAR barrier. By the time the affirmative had been given, the F-16 had already rolled over the SAFE BAR which was still out of battery and down, and the tailhook actually snagged the system's webbing laying on the ground in the overrun, stretching the webbing until it eventually failed (SAFE BAR not designed for any hook engagements). The jet was only travelling about 55 kts or so at this time, and nearing the end of the overrun towards where the LOC antenna were sitting, is where he decided to eject, with 0 AGL and ~50 knots, more than enough for the seat to function properly, and it took him to about 300 AGL. Calm winds, and the aircraft being stopped by digging into the soft grass, as well as impact with the LOC antenna, were the right combo to take him into the fire.
Where pilot error came into the decision factor, was due to the abort procedures not being accomplished in a timely manner. From what I remember from way back, abort for the Viper is generally Idle, hook down, aft stick, speedbrakes open, max wheel braking as required. In his case, the hook wasn't lowered for nearly 3000' ground roll after the abort was initiated, taking him past the BAK-12 before the hook came down and giving him no chance to engage it. And max braking was not utilized, nor full aft stick to improve that braking. Engineering analysis showed that lowering the hook in a timely manner would likely have resulted in engaging the BAK-12, and even if that was missed, max braking should've stopped the aircraft at or near the end of the runway. Contributing to all of the above missed items, are had the pilot requested Barrier over tower freq and/or had the pilot made the abort call over tower UHF instead of interflight VHF, or had the tower raised it in a timely manner, the SAFE BAR would definitely have stopped his aircraft; but it is likely the pilot either didn't know it was available, or knew but didn't believe it to be an F-16 compatible system.
Sad part of the accident is, after very detailed engineering analysis, it is completely unknown to this day what the reason for the abort ever was. No problems with the aircraft or any component of the aircraft pre-impact, was ever found during the investigation.
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///AMG
Well-Known Member
Couple thoughts. First being that the CAPs for the viper on an abort are "1. Throttle idle, 2. Hook down (if req'd)" That's it. Obviously the -1 has more to say about it, and nobody is going to simply do those two steps only and expect to stop during a high speed abort. But still, it is what it is. Second, in the F/A-18 community, we have had a rash of high speed aborts for no reason that have resulted in class A/B/C damage due to ensuing brake fire transferring to the rest of the airframe. Most have been the result of high gross weight takeoffs that don't "feel right" to folks accustomed to CL drop tank and otherwise clean takeoff rolls in jets that now have a bunch of ordnance hanging, in hot weather, at higher elevation than they are used to. No idea if 36k is a "normal" standard ops takeoff gross for a C/D F-16, but that is on the heavy side for what I am used to, flying slick A's and B's (which are presumably much much lighter in terms of basic weight). Again in the A/B world, I have heard of and seen engine malfunctions that were not represented by MFL's or the two little DEEC bit balls. I high speed aborted for an uncontrollable right drift on takeoff, and did an SFO to low key for EGT being well outside limits immediately upon rotation. Neither case was reported by any fault monitoring in the jet.
Yeah these are C/D Block 50s with the bigger GE engines, which will be notably heavier than your A/B slicks (you running Block 10s?), hence the heavier weight. Thing that sucks in this accident is that the jet could've been stopped not only by normal abort, but potentially by the long-field gear, and definitely by the departure end barrier. But, as the Swiss cheese model usually goes...
Bandit_Driver
Gold Member
It may be different in the fighter world. But in commercial we are trained pretty much to take almost anything into the air once in the high speed portion of the take off.
Outside of serious motor problem what else do the fighters consider a high speed abort for?
Do you guys practice pitch and power? If all instrument quit? I had to do that once in the sim. They failed everything except the engine gauges and standby adi and made us fly to vmc conditions.
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Outside of serious motor problem what else do the fighters consider a high speed abort for?
Do you guys practice pitch and power? If all instrument quit? I had to do that once in the sim. They failed everything except the engine gauges and standby adi and made us fly to vmc conditions.
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For birds like the F-16, F-35, etc.....an engine problem on takeoff is pretty self explanatory in that you aren't going anywhere airborne, or going anywhere far for that matter.
On a jet like the A-10, I was pushing a ~45,000 lb TOW jet with two 8,900 lb/thrust motors, so loss of one on takeoff......a PA-44 had a better single engine climb rate, as I wouldn't have time for fuel dumping, and stores jettison wouldn't buy me too much more VVI.
To your question, it depends on the aircraft. There first needs to be a clear brief of what will be a high speed abort and what won't be. For the F-117, there was one particular emergency on takeoff.....dual generator failure with takeoff into IMC....that would need to be an abort, even if high speed. Because that one emergency, simply due to the number of items lost and the number of items you are left with, was a guarantee that you will lift off to your death or to an ejection scenario; you would not be coming back with the jet, for a variety of reasons. And even if you did manage to get airborne with the minimal systems available, you'd better be back on the ground in about 10-15 mins, or otherwise you will lose the jet again and will be coming down by parachute, after the battery fails. But that was systems knowledge, and quick assessment skills requirement.
It just depends by aircraft, conditions on takeoff, what the EP is, etc. Its not good to get airborne in an aircraft that you know won't fly or won't fly for long (onboard/cabin fire, structural failure/damage, etc) and end up taking off to your own death; and neither is it good to do a high speed abort for a warning light or master caution, crashing off the end of the runway and killing yourself, and it turns out to have been an antiskid light or some other nuisance light.
The worst one for me personally, would be a scenario where I got airborne in a sick jet that wouldn't fly or fly for long, near a populated area, that I either ended up riding into that area, or jumping out of it and it heading into that area. To me, as a pilot, I not only have a responsibility to myself and any pax I would have onboard, but I also have a responsibility to those on the ground who will be injured/killed were my plane to be dropped into their neighborhood or place of work, etc. Those are things I would consider also, depending where I am, on what I may accept a high speed RTO for in one place, vs where I may make a go decision in others. To me, that comes under airmanship.
In my F-117 example, that emergency I speak of, it was an abort even if past V1, merely because of the guarantee that you'd be taking off to your death or to someone elses death, or to a parachute recovery at best. The difference there, was that we had the luxury of a drag chute and an arrestor hook, and at some places, a full barrier raise at the departure end. That's not an option for many, I understand; but my primary point is knowing your aircraft, it's systems, what constitutes a no-kidding "I'd better not lift off with this emergency", and a good pre-takeoff brief based on conditions being encountered for that takeoff.
There are indeed some emergencies that are best kept as ground emergencies, and others that are better handled as air emergencies.......depending on a whole host of factors in the mix.
Bandit_Driver
Gold Member
Thanks Mike.
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ryan1234
Desensitized Member
We took a cable a couple days ago, granted it was a UTL-A in the air. However, it's nice having two motors for take-off EPs.
I guess the good thing for you guys taking off in an A-10 is that you have about 5 minutes between brake release and rotation to consider any EPs and about 5 more minutes before you pass the end of the runway - and you may not ever hit the max engagement speed of the BAK-12 before the last cable.
Lawman
Well-Known Member
We took a cable a couple days ago, granted it was a UTL-A in the air. However, it's nice having two motors for take-off EPs.
I guess the good thing for you guys taking off in an A-10 is that you have about 5 minutes between brake release and rotation to consider any EPs and about 5 more minutes before you pass the end of the runway - and you may not ever hit the max engagement speed of the BAK-12 before the last cable.
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We took a cable a couple days ago, granted it was a UTL-A in the air. However, it's nice having two motors for take-off EPs.
I guess the good thing for you guys taking off in an A-10 is that you have about 5 minutes between brake release and rotation to consider any EPs and about 5 more minutes before you pass the end of the runway - and you may not ever hit the max engagement speed of the BAK-12 before the last cable.
If we had a hook on the Hog, so no BAK-12 for us, other than something to run over on takeoff/landing. We could, however, take an MA-1A or BAK-15 or SAFE BAR, but would probably bounce out of it backwards, from the recoil of going into it.
///AMG
Well-Known Member
Concur with mike. In the Hornet/Super Hornet, we feel the same way……..only real time you might abort is dual fire lights, dual bleed warning lights (normally a precursor to a big fire in the keel that isn't likely to go out), or failure to rotate by planned takeoff airspeed. In a single engine jet like the Viper, if that motor isn't working, you want to keep it on deck or potentially put it back down on deck if you can stop before the overrun. Engine fire is more of a grey area, as some of those are purely afterburner related and once out of AB, they go out. But if I'm on fire on the takeoff roll, I'm going to stop if I can. As simple as the F-16A/B is, I can't think of much else other than power plant problems, complete loss of hydraulics, or no response from the flight controls that would really be in my high speed abort category. Pitch+power really doesn't work as well in fighter aircraft. I think I could probably get the thing back down on deck safely without an airspeed indicator, but the equation and sight picture isn't as cut and dry as it is in other aircraft. The sight picture between 150 knots and 800 knots isn't that visually apparent, and you don't have much in the way of control feel differences other than some artificial inputs. In the gear/flaps down landing configuration, it is a bit easier. For the Viper, I know about what RPM gives me a normal approach, in the F/A-18, I know it more by feel and muscle memory of the throttle position after a lot of years/hours flying it. But no, it isn't practiced. If you have a true air data computer failure (vs just a gauge/indication failure), a digital FBW/CBW jet is going to have some significant degradation in FCS operation and control response/gains, so that compounds the problem, and generally will give you a flight control mode that you are not familiar with, along with some responses that are not familiar, fixed gains, open loop processing, etc.
@ mike, we fly block 15's, so -220 motors, DEEC, and MLU, along with the stab mod for departure resistance/recovery characteristics. Think there were some other things too, but those are the high points.
Springer
Well-Known Member
Sounds like McDonald Douglas kept the same system for your F-15 as the F-4. I took an approach end cable for the same failure.....Utility Hyd.