Minimum Height for 180° Auto in the Cruise
Thread Starter
Minimum Height for 180° Auto in the Cruise
Wondering what opinion the good folk may have, and you bad ones as well. 
The Oz Army I'm told used to teach their Kiowa pilots 360° autos initiated on the tree tops in the cruise, for the time when low flying and the failure occurred just as you passed over the only clear spot. In training we always did cruise 180° from 1,000, 360° from 1,500 irrespective of type.
I ask the question because of my flying offshore in the 205 and in my dotage wondering how far out I hung my sweet little *** in the doing, thinking of the days with 60 knots or so tailwind.
The Oz Army I'm told used to teach their Kiowa pilots 360° autos initiated on the tree tops in the cruise, for the time when low flying and the failure occurred just as you passed over the only clear spot. In training we always did cruise 180° from 1,000, 360° from 1,500 irrespective of type.
I ask the question because of my flying offshore in the 205 and in my dotage wondering how far out I hung my sweet little *** in the doing, thinking of the days with 60 knots or so tailwind.
There used to be a film, shown to us "envious" Huey drivers, of two Kiowas (Kiowae?) galloping along at treetop level. Both chopped their throttles, one zoomed and then travelled for a mile further before touching down, the other zoomed up into a 360 and landed under where the throttle was cut. Impressive.
For currency, us Huey pilots had to fly downwind at 1000', 90kt, and as we passed over a 100' circle on the grass below, enter auto, do a 180, and touchdown inside the circle and stop the skid inside the circle. The penalty for going through the circle was a loss of captaincy and re-training. Dictated by the dicheads at OpCom.
The CO put up with this for a few cycles, but then got the 5h1ts with it. He pulled everybody in, got 3 Hueys and 3 instructors, and the whole squadron did the test. The CO and one of the qfi failed, as did quite a few of the senior pilots, and the ones who did best were the newly-arrived boggies fresh off conversion. The CO declared the squadron to be non-operational due to lack of captains, and sent the message to OpCom with some choice words. The reply came rocketing back, scratch the test results, forget we ever asked, you are all back on line.
While doing this test, we asked one of the ace instructors, whose nickname was something like an arachnid, if he could land on a matchbox (on its side) in the middle of the circle.
"Of course!"
Off a 360 from 1000'?
"Of course! Which skid do you want on it?"
We let him have the left skid, and away he went, into wind. Full 360, and as he pulled pitch at the end, the matchbox blew over and he skimmed its side.
For currency, us Huey pilots had to fly downwind at 1000', 90kt, and as we passed over a 100' circle on the grass below, enter auto, do a 180, and touchdown inside the circle and stop the skid inside the circle. The penalty for going through the circle was a loss of captaincy and re-training. Dictated by the dicheads at OpCom.
The CO put up with this for a few cycles, but then got the 5h1ts with it. He pulled everybody in, got 3 Hueys and 3 instructors, and the whole squadron did the test. The CO and one of the qfi failed, as did quite a few of the senior pilots, and the ones who did best were the newly-arrived boggies fresh off conversion. The CO declared the squadron to be non-operational due to lack of captains, and sent the message to OpCom with some choice words. The reply came rocketing back, scratch the test results, forget we ever asked, you are all back on line.
While doing this test, we asked one of the ace instructors, whose nickname was something like an arachnid, if he could land on a matchbox (on its side) in the middle of the circle.
"Of course!"
Off a 360 from 1000'?
"Of course! Which skid do you want on it?"
We let him have the left skid, and away he went, into wind. Full 360, and as he pulled pitch at the end, the matchbox blew over and he skimmed its side.
Standard Brit Mil was 1000' for 180 and 1500 for 360 but that was in the Gazelle, entering at 90 kts and using a standard 60 kts and 30 deg AoB, so it was an academic manoeuvre used to teach the basic handling skills before moving to PFLs.
Changing speed and AoB from the academic ones could get you round much quicker.
Changing speed and AoB from the academic ones could get you round much quicker.
For the average pilot a 360 auto is prone to give you a lot of trouble:
1/ Because of the turning load factor, Rotor RPM will creep up and you are likely to increase the collective too much in a rush to reduce RRPM, consequently to the collective increase the AC will pitch up and worsen that problem further.
2/ Because of all that turning you might loose your landing spot (talking of an average pilot focused of regulating the auto)
3/ Keeping in trim in a 360 auto is also a task that is often missmanaged
for an average skill level I find it much more applicable to
1/ reduce the speed to a hover auto, the flare will help get your RRPM right even if it had decayed due to possible slow reaction time, (talking about a real case, where collective down response is not a perfect motor reflex)
2/ do a pedal turn to find your spot
3/ than heavy nose down to get 50knots before the ground proximity
1/ Because of the turning load factor, Rotor RPM will creep up and you are likely to increase the collective too much in a rush to reduce RRPM, consequently to the collective increase the AC will pitch up and worsen that problem further.
2/ Because of all that turning you might loose your landing spot (talking of an average pilot focused of regulating the auto)
3/ Keeping in trim in a 360 auto is also a task that is often missmanaged
for an average skill level I find it much more applicable to
1/ reduce the speed to a hover auto, the flare will help get your RRPM right even if it had decayed due to possible slow reaction time, (talking about a real case, where collective down response is not a perfect motor reflex)
2/ do a pedal turn to find your spot
3/ than heavy nose down to get 50knots before the ground proximity
The following users liked this post:
than heavy nose down to get 50knots before the ground proximity
for an average skill level I find it much more applicable to
1/ reduce the speed to a hover auto, the flare will help get your RRPM right even if it had decayed due to possible slow reaction time, (talking about a real case, where collective down response is not a perfect motor reflex)
2/ do a pedal turn to find your spot
3/ than heavy nose down to get 50knots before the ground proximity
1/ reduce the speed to a hover auto, the flare will help get your RRPM right even if it had decayed due to possible slow reaction time, (talking about a real case, where collective down response is not a perfect motor reflex)
2/ do a pedal turn to find your spot
3/ than heavy nose down to get 50knots before the ground proximity
I think I'd stick to 360s!
Wow! That sounds scary. A pedal turn in an auto? Never even heard of that! And isn't that pitch-down asking for mast bumping in some types?
I think I'd stick to 360s!
I think I'd stick to 360s!
Once I got the hang of it, I became much more consistent in hitting the spot and I really appreciate not having the feeling of my stomach between my ears.
No problems of mast bumping at all, there is no hard push over and the tailrotor can not push you into a roll, since it does not produce a lot of thrust. Just enough to overcome the friction of the system, but not the whole torque of the engine.
Take a instructor and try it. Just a new tool in your box. Really helpful. BTW, you can even go backwards for a while to hit the spot better.
The following users liked this post:
Right, my lowest 180 was from about 500' in an R22 to a clearing on a hill with power recovery. The instructor and I worked our way down from 1000' down in small steps, but in the end the flare started in the turn. Just gives one more confidence in the capability of the machine and yourself.
In real life, I would recommend not flying lower than 1000'. 3000' is my go to altitude today for cruise.
In real life, I would recommend not flying lower than 1000'. 3000' is my go to altitude today for cruise.
This discussion seems to beg some careful consideration of several factors beginning with the type of aircraft being flown, pilot experience, training, and proficiency for starters followed by airspeed, height above ground, and wind direction/velocity..
During my flight training we learned to how to operate very close to the ground in what was called Low Level Flight Ops which later was expanded to become known as Nap of the Earth flight that was quite different than low level flyingl
The difference being NOE varied airspeed for different height above the ground where low level was done at normal cruise speed.
Initially we learned to apply aft cyclic and up collective to provide a "zoom" climb (if any helicopter can be accused of "zooming" speed wise) to 300-5000 feet and then a normal autorotation could be initiated to include a 180 degree turn.
It must be remembered the aircraft involved had high inertia rotor systems.
Later, a wild haired Aussie Check Captain demonstrated a much different method....which involved an abrupt pull up and a pedal turn at the top much like a stall turn.....and landing back on a spot " behind" us.
That was worked fine so long as one was at a high airspeed and low height when initiated and reacted very quickly.
The benefit of these kinds of discussions is they remind us that one system's dogma might not be the only answer to the question and that some systems are far too regimented.
We can all learn from others....we just have to be careful what we learn from them.
If you are going to experiment be sure to do so very carefully and apply that new learning with caution.
One precaution I take which has been very successful is never to get inside a Robbie for any reason.
I have done low level 180 degree autorotations in Jet Rangers, Hughes 500's right on up to the Chinook and the techniques work.
That being said....being current, proficient, and practiced is the key.....but who is all of that when it comes to an engine failure when you are low and slow?
Do you know what the normal rate of descent is for your particular aircraft is? Is your aircraft properly rigged and the Auto Rev's confirmed to be as they should be by an air test?
During my flight training we learned to how to operate very close to the ground in what was called Low Level Flight Ops which later was expanded to become known as Nap of the Earth flight that was quite different than low level flyingl
The difference being NOE varied airspeed for different height above the ground where low level was done at normal cruise speed.
Initially we learned to apply aft cyclic and up collective to provide a "zoom" climb (if any helicopter can be accused of "zooming" speed wise) to 300-5000 feet and then a normal autorotation could be initiated to include a 180 degree turn.
It must be remembered the aircraft involved had high inertia rotor systems.
Later, a wild haired Aussie Check Captain demonstrated a much different method....which involved an abrupt pull up and a pedal turn at the top much like a stall turn.....and landing back on a spot " behind" us.
That was worked fine so long as one was at a high airspeed and low height when initiated and reacted very quickly.
The benefit of these kinds of discussions is they remind us that one system's dogma might not be the only answer to the question and that some systems are far too regimented.
We can all learn from others....we just have to be careful what we learn from them.
If you are going to experiment be sure to do so very carefully and apply that new learning with caution.
One precaution I take which has been very successful is never to get inside a Robbie for any reason.
I have done low level 180 degree autorotations in Jet Rangers, Hughes 500's right on up to the Chinook and the techniques work.
That being said....being current, proficient, and practiced is the key.....but who is all of that when it comes to an engine failure when you are low and slow?
Do you know what the normal rate of descent is for your particular aircraft is? Is your aircraft properly rigged and the Auto Rev's confirmed to be as they should be by an air test?
The following users liked this post:
Instructors love to show off and a 500' 180 is a party trick when you know when the 'engine failure' is going to happen - in the real case there will be a delay, the Nr will decay and the punchy flare will be needed to recover that Nr - the chances of making a 180 to EOL following a real engine failure from that condition are slim.
As for the low speed auto - again a standard technique taught in Brit Mil as an alternative to a 360, particularly for strong winds when a 360 would drift you a long way down wind.
On most aircraft the speed was brought back to 20 to 30 Kts (the ASI is pretty useless then anyway) and you held it until the wind blew you backwards (relative to the ground) enough for you to see the landing spot. With the Gazelle you could use the balance string to indicate zero IAS as it would point upwards.
You just had to give yourself enough height to make the recovery back to bucket speed if you wanted to have a chance of the RoD (which will increase markedly at low speed) to stabilise back to normal auto RoD. 1000' to 1200' was usually recommended for training.
Flying with other pilots and having PFL competitions, where the NHP calls the entry and aiming point, is a great way to build awareness and skill.
The more basic turning autos you do, the better will be your Nr control - if you learn to anticipate how loading the disc will increase the NR and vice-versa, you will make the small collective corrections to prevent rather than correct Nr excursions.
As for the low speed auto - again a standard technique taught in Brit Mil as an alternative to a 360, particularly for strong winds when a 360 would drift you a long way down wind.
On most aircraft the speed was brought back to 20 to 30 Kts (the ASI is pretty useless then anyway) and you held it until the wind blew you backwards (relative to the ground) enough for you to see the landing spot. With the Gazelle you could use the balance string to indicate zero IAS as it would point upwards.
You just had to give yourself enough height to make the recovery back to bucket speed if you wanted to have a chance of the RoD (which will increase markedly at low speed) to stabilise back to normal auto RoD. 1000' to 1200' was usually recommended for training.
Flying with other pilots and having PFL competitions, where the NHP calls the entry and aiming point, is a great way to build awareness and skill.
The more basic turning autos you do, the better will be your Nr control - if you learn to anticipate how loading the disc will increase the NR and vice-versa, you will make the small collective corrections to prevent rather than correct Nr excursions.
The following 6 users liked this post by Gordy:
Thread Starter
two Kiowas (Kiowae?) galloping along at treetop level. Both chopped their throttles, one zoomed and then travelled for a mile further before touching down, the other zoomed up into a 360 and landed under where the throttle was cut. Impressive
How about the grass Gordy to save skid wear, or is it full of gopher holes? Nice video.
chasing Nr, always found it a difficult task in the 76 with glass cockpit, never did get a handle on it, with steam gauges no problem.
Coyle, Shawn. LIttle Book of Autorotations . Eagle Eye Solutions LLC.
That left a confortable 750ft to regain forward speed.
An auto that starts well has much better chance to finish well, I found those 12 seconds helpfull to recover and get my ducks in row.
One can actually practice or demonstrate this at low risk, enter an auto and maintain a long gentle flare and see how long you can maintain altitude.
it is always more time than I expected and a good alternative to the 3,2,1 collective down cyclic aft to keep level attitude that is always taught.
I used to do them pretty regularly on light helicopters from 500ft in the cruise but it was worked down from a higher height and more of a demo to students as your reactions had to be bang on not having inertia to play with.
I always thought 800ft was a realistic height for an unforeseen event even then you have to be pretty quick.
I’m pretty sure the closest I’ve come to death in a helicopter involved a 500ft throttle chop on a very windy day. While in the turn I encountered severe wind shear and recovered high speed low rpm about 2ft off the ground. Lesson learnt…. Be careful playing out there.
I always thought 800ft was a realistic height for an unforeseen event even then you have to be pretty quick.
I’m pretty sure the closest I’ve come to death in a helicopter involved a 500ft throttle chop on a very windy day. While in the turn I encountered severe wind shear and recovered high speed low rpm about 2ft off the ground. Lesson learnt…. Be careful playing out there.
I have done auto entries in a light-ish 44 on a thermally day, and quite often it floats like a competition glider - takes ages for any RoD to appear at all. Not quite ‘bring something to read’, but certainly lacking drama.
Things to note on Gordy's video are:
Entry height is only 750'agl (starts at 1000 and lands at 250')
The Low Nr warning is on for most of the turn (not unsafe and I suspect well within limits) but decays further when the nose is pushed down to recapture the speed (negative flare effect)
The RoD is still high (2500' fpm) as he starts the flare - that is why I mentioned recovering to bucket speed with enough height to let the RoD settle back to normal - again not a problem in a light aircraft for training but you reduce your margins in a heavier and less capable aircraft for a safe EOL if you have a higher RoD.
The only time I can think you would use this technique for real is if the only landing area is pretty much right underneath you and the wind isn't too strong when the donk stops. A good handling exercise though.
Entry height is only 750'agl (starts at 1000 and lands at 250')
The Low Nr warning is on for most of the turn (not unsafe and I suspect well within limits) but decays further when the nose is pushed down to recapture the speed (negative flare effect)
The RoD is still high (2500' fpm) as he starts the flare - that is why I mentioned recovering to bucket speed with enough height to let the RoD settle back to normal - again not a problem in a light aircraft for training but you reduce your margins in a heavier and less capable aircraft for a safe EOL if you have a higher RoD.
The only time I can think you would use this technique for real is if the only landing area is pretty much right underneath you and the wind isn't too strong when the donk stops. A good handling exercise though.
Just for the record......the RPM Warning can be for low or high Rotor RPM and there is an associated Warning Audio sound for certain low RPM situations.
From the UH-1 Operators Manual
From the UH-1 Operators Manual
2-85. RPM High-Low Limit Warning System. The rpm high-low limit warning system provides the pilot with an immediate warning of high and low rotor or engine rpm. Main components of the system are a detector unit, warning light and audio signal circuit, low RPM AUDIO/OFF switch, and electrical wiring and connectors. The warning light and audio warning signal systems are activated when any one of the following rpm conditions exist:
a Warning light only:
(1) For rotor rpm of 329-339 (High Warning).
(2) For rotor rpm of 300-310 (Low Warning).
(3) For engine rpm of 6100-6300 (Low Warning).
(4) Loss of signal (circuit failure) from either rotor tachometer generator or power turbine tachometer generator.
b. Warning light and audio warning signal combination:
(1) For rotor rpm of 300-310 and engine rpm of 6100-6300 (Low Warning).
(2) Loss of signal (circuit failure) from both rotor tachometer generator and power turbine tachometer generator.
a Warning light only:
(1) For rotor rpm of 329-339 (High Warning).
(2) For rotor rpm of 300-310 (Low Warning).
(3) For engine rpm of 6100-6300 (Low Warning).
(4) Loss of signal (circuit failure) from either rotor tachometer generator or power turbine tachometer generator.
b. Warning light and audio warning signal combination:
(1) For rotor rpm of 300-310 and engine rpm of 6100-6300 (Low Warning).
(2) Loss of signal (circuit failure) from both rotor tachometer generator and power turbine tachometer generator.