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[omega2018]

its seems the airport is only 7 feet amsl so assuming the crash site is similar he was only 307 feet out.  500 feet agl starting point for the maneouvre is the minimum he is licensed for mind. 

[aaronjb]

All cyclists who crash in to cars and kill the occupants should be.  Gits they are

All cyclists should be tried for something.  Give me time and I'll figure out what it should be 

So anyone who kills someone in a car crash should also be tried for murder then?

Some people......

I know some people who truly believe that Possibly not helped by the fact that we're all told now there is "no such thing as an accident" (it's an "incident") and someone is always at fault because where there's blame there's a claim...

[edit] I am, of course, in no way saying the pilot should be tried for murder.  I'm sure if it turns out he was at fault because he failed to realise his altitude then he'll end up being tried for something, even though he'll have to live with the guilt (guilty or not!) for the rest of his life.

[steve6367]

Has anyone thought that he might have mixed up meters and feet?  I am pretty sure the Hawker works in old money and most of the planes he works on with BA are likely to be in meters.

All aviation in the UK and internationally works in "old money" although I've flown gliders from Europe with metric instruments, which are confusing. If he flew any types with metric instruments he would have been well used to converting to and from feet as that's what air traffic control work in. A Hunter wouldn't have been fitted with metric instruments.

The Fail have jumped to the conclusion that the pilot was at error, but I can't see anything of that in the AAIB bulletin.

The only altitude reference is from secondary radar, which has an altitude resolution of 100 feet, isn't referenced to QNH of the day and the report mentions the 6 second update rate. A lot can happen in 6 seconds, certainly, a gentle climb from 200 to 500 feet before entering the loop wouldn't have been apparent from that data. Secondary radar is designed to identify aircraft at cruising flight levels. Who knows how accurate it is that close to the ground?

I don't actually believe the entry height of the manoeuvre is relevant. Whilst an aircraft with low wing loading and low or no thrust such as a glider essentially conserves energy through a loop, exiting at close to the entry height and speed if flown properly, an aircraft with a high wing loading such as the Hunter would be very "lossy", relying on thrust throughout the manoeuvre.

The interesting thing would be to know his height and speed at the top of the loop. Here he would decide if he could "pull through" the vertical axis and recover level flight safely above the ground, and he would have the opportunity to roll back level and abort the figure if not.

It is relevant in so far as had he started at or above the minimum height  he would have gained more time to deal with any problem. The top of the loop was 2600ft, 100KIAS.

[omega2018]

the reports didn't seem sure about the height of the loop "The maximum
altitude recorded during the final manoeuvre was 2,600 ft amsl (recorded by Heathrow
radar), which may not reflect the peak altitude achieved because the radar data was not
continuous."

hopefully the cameras will show it or it can be calculated from the imges, if so it's strange it isn't in the initial report.

i'm surprised the jet didn't seem to have the power to pull up at the end given the rate of climb of the hunter is apparently 87m/s and it has a reasonably high thrust to weight ratio - it clearly stalled at the end

[LC0112G]

its seems the airport is only 7 feet amsl so assuming the crash site is similar he was only 307 feet out.  500 feet agl starting point for the maneouvre is the minimum he is licensed for mind.

It's a grey area, and display pilots don't seem to agree on what the rule means. The limit for flypasts was 100'. The limit for aerobatics was 500'. So what happens if you perform a flypast and then go straight into a loop? Some display pilots seem to be saying it is acceptable to perform the flypast at 100', and then pull up into a loop, but the loop must be completed without busting the 500' deck on the way back down. To ensure that happens the pilots should fly to a system of 'gates' whereby they must ensure they reach a certain altitude and speed at the TOP of the loop before they attempt to complete the second half of the manouver - i.e.the way down. If the gate height/speed isn't reached, then the manouver should be thrown away - that is the pilot should continue to build height/speed before starting to come back down.

So the important bit of the report isn't that the start of the loop was at 200' - but rather that the top of the loop was 2800' and 100kts. I have yet to see any qualified Hunter display pilot say if this is an acceptable 'gate' for such a loop. The further complication is that it wasn't a 'loop' - or if it was, it wasn't flown correctly. It may have been a quarter clover - or some variation of a modified quarter clover. Different manouvers require different gate parameters because the additional rolling involved steals energy.

[LC0112G]

i'm surprised the jet didn't seem to have the power to pull up at the end given the rate of climb of the hunter is apparently 87m/s and it has a reasonably high thrust to weight ratio - it clearly stalled at the end

Power is largely irrelavent when pulling out at the bottom of the manouver. Whilst the nose is pointed downwards, power just increases your speed towards the ground - and gravity is already pulling you down. What you need is lift - which can only come from getting the wings level. Similarly too much speed/power over the top of a loop is a bad thing, since that extra speed will increase the radius of your (vertical) turn, meaning you need more altitude the faster you're going.

Once you go past the top of the loop, and your nose is pointed down past around 45 degrees then your fate is sealed. Too much speed, or not enough altitude at that point and you've had it. 

[steve6367]

its seems the airport is only 7 feet amsl so assuming the crash site is similar he was only 307 feet out.  500 feet agl starting point for the maneouvre is the minimum he is licensed for mind.

It's a grey area, and display pilots don't seem to agree on what the rule means. The limit for flypasts was 100'. The limit for aerobatics was 500'. So what happens if you perform a flypast and then go straight into a loop? Some display pilots seem to be saying it is acceptable to perform the flypast at 100', and then pull up into a loop, but the loop must be completed without busting the 500' deck on the way back down. To ensure that happens the pilots should fly to a system of 'gates' whereby they must ensure they reach a certain altitude and speed at the TOP of the loop before they attempt to complete the second half of the manouver - i.e.the way down. If the gate height/speed isn't reached, then the manouver should be thrown away - that is the pilot should continue to build height/speed before starting to come back down.

So the important bit of the report isn't that the start of the loop was at 200' - but rather that the top of the loop was 2800' and 100kts. I have yet to see any qualified Hunter display pilot say if this is an acceptable 'gate' for such a loop. The further complication is that it wasn't a 'loop' - or if it was, it wasn't flown correctly. It may have been a quarter clover - or some variation of a modified quarter clover. Different manouvers require different gate parameters because the additional rolling involved steals energy.

A Hunter won't do that, if it comes out at the entry height then the manoeuvre has gone well.

[Kevin Wood]

I have yet to see any qualified Hunter display pilot say if this is an acceptable 'gate' for such a loop.

That's the bottom line.

If he missed the gate, then he had an opportunity to avoid the accident. If he didn't, then something went wrong on the way down, that he may have not been able to do anything about..

[Lazydocker]

I have yet to see any qualified Hunter display pilot say if this is an acceptable 'gate' for such a loop.

That's the bottom line.

If he missed the gate, then he had an opportunity to avoid the accident. If he didn't, then something went wrong on the way down, that he may have not been able to do anything about..

I'll wait for detailed reports before judging But, IMO, something looks off about 1/4 of the way down the second half of the "loop", although it could be camera trickery

[LC0112G]

A Hunter won't do that, if it comes out at the entry height then the manoeuvre has gone well.

It will - If you go in at 500kts 100' full throttle, you can go up and over the top, throttle back, and complete the loop above entry height. Effectively you're trading initial kinetic energy (speed) for final potential energy (altitude) - and all the engine has to do is replace the energy lost to drag. Since we know the engine must be able to produce more thrust than there is drag (otherwise the plane would never get off the ground) then the extra thrust on the way up will also add to the exit altitude. 

[omega2018]

Power is largely irrelavent when pulling out at the bottom of the manouver. Whilst the nose is pointed downwards, power just increases your speed towards the ground - and gravity is already pulling you down. What you need is lift - which can only come from getting the wings level.

i'm surprised at that for a fighter aircraft, even for an old one.  i would have thought if you put on full power and pull back on the stick it would pretty sharply turn up, not increase your speed towards the ground. 

even if the stick is pulled back too much i'd expect it to be more difficult to stall the jet than it appeared, providing power was on full.   at the end it looks like he pulled back without power and it fell like a stone. didn't hear any engine noise increase. 

[LC0112G]

Power is largely irrelavent when pulling out at the bottom of the manouver. Whilst the nose is pointed downwards, power just increases your speed towards the ground - and gravity is already pulling you down. What you need is lift - which can only come from getting the wings level.

i'm surprised at that for a fighter aircraft, even for an old one.  i would have thought if you put on full power and pull back on the stick it would pretty sharply turn up, not increase your speed towards the ground. 

even if the stick is pulled back too much i'd expect it to be more difficult to stall the jet than it appeared, providing power was on full.   at the end it looks like he pulled back without power and it fell like a stone. didn't hear any engine noise increase.

Lift can only come from two sources - the wings providing aerodynamic lift, and/or the engine thrust being pointed downwards.

The axis of engine thrust is basically in line with the fuselage. If the nose is pointed down, then simple physics says a proportion of that thrust is accelerating the plane towards the ground. This doesn't stop until the fuselage is level, at which point all the thrust is accelerating the aircraft forwards. If you're coming down off a loop, then gravity is already accelerating you towards the ground, so you don't really want the engine thrusting you even faster downwards. AIUI, the normal technique is full power from 6 to 10 o-clock (to gain height), then ease off the throttle between 11 and 12 o-clock on the way up, and then feed the throttle back in again at about 5 o-clock on the way down (once you know you're pulling out successfully).   

The Hunter isn't a particularly powerful aeroplane - not when compared to a modern jet like an F-16, Typhoon or Tornado or F-4.  Pulling hard on the stick will create a lot of drag, which will cause a loss of speed/energy. If the engine isn't producing enough thrust to overcome the loss of energy then the plane will eventually stall. There is an optimum speed and power setting to achieve a min radius turn/loop - but the critical point is not at the bottom - it's at the top. If you don't hit your gate speed/altitude then it doesn't matter what you do on the way down you are going to bust the minimums.

There was a fatal F-4 phantom crash on the practice day for RAF Abingdon back in the late 80's. The main factor was found to be that the pilot had spent too long with the throttles full open at the top of the loop. This meant that his speed through the "gate" was too high, and therefore the radius of the turn in the second half of the loop was wider than he expected, and ultimately greater than the altitude available to recover.

Everyone needs to wait for the full AAIB report before coming to any conclusions here. 

[Kevin Wood]

The Hunter isn't a particularly powerful aeroplane - not when compared to a modern jet like an F-16, Typhoon or Tornado or F-4.

Exactly.. and quite heavy too.

Pulling hard on the stick will create a lot of drag, which will cause a loss of speed/energy.

Also very significant. If your basic problem is a lack of energy, you are better off not loading the wings heavily too close to the stall, as the whole thing becomes very draggy, losing you more energy. Better to do what he did, and pull steadily, keeping the airframe efficient, until it becomes a last ditch attempt to avoid the ground.

The AoA looked very high in the last stages, and it was just dropping a wing as he crashed, so I'm guessing he probably pulled harder and stalled at that point. The drag induced at that point probably lost him some energy and made the crash more survivable, It also pitched the nose up so the tail contacted first. That probably saved his life, but I'd bet there was nothing he could have done for the other victims at any point during the last half of the loop.

Everyone needs to wait for the full AAIB report before coming to any conclusions here.

Amen to that.

[steve6367]

A Hunter won't do that, if it comes out at the entry height then the manoeuvre has gone well.

It will - If you go in at 500kts 100' full throttle, you can go up and over the top, throttle back, and complete the loop above entry height. Effectively you're trading initial kinetic energy (speed) for final potential energy (altitude) - and all the engine has to do is replace the energy lost to drag. Since we know the engine must be able to produce more thrust than there is drag (otherwise the plane would never get off the ground) then the extra thrust on the way up will also add to the exit altitude.

I personally think that would be exceptionally difficult in a Hunter, for some of the reasons you highlight in your next reply. As you also say though we are not going to know anything for sure until the investigation progresses and produces a final report.

[Rods2]

He also wouldn't be the first pilot to be trying too hard to pull out of such a situation, where a high AoA / drag situation rapidly reduces speed (without the pilot increasing throttle and power) and increases your sink rate.