Spiral dive up to vNE (CPL instruction)

[Skeeve]

Hi,

the current EASA NPA for flight training (NPA 2014-29) requires (among other things) "Flight at critically high airspeeds, including recognition of and recovery from spiral dives".
The AMC elaborates: "flight at critically high airspeeds (approaching VNE) and recognition of, and recovery from, spiral dives. These manoeuvres are often combined; the examiner may put the aeroplane into a steep dive or a spiral dive with speed increasing rapidly and hand control to the candidate to initiate appropriate recovery action either to straight and level flight or into a climb."

This appears to ruffle some feathers outside the UK (deeming it a too dangerous maneuvre to carry out).

As the current Flight Examiners Handbook and the Standards Document also have this requirement (and VERY similar wording), I am curious what the experience of the UK FI and FE are regarding training and testing the spiral dive with approach to vNE on a regular basis.

How do you do it? Do you know how old this requirement is in the UK?
Any accidents associated with the spiral dive manoeuvre?

Thomas

[Genghis the Engineer]

Roll and push to enter, pull and roll to recover, watch the g.

Personally, I like to also demonstrate high speed flight wings-level, so that students know what that particular corner of the flight envelope looks like as well.

I know instructors who like to let you get yourself into a spiral dive through deliberately letting you overbank with a dropping nose, to make a point.

Nope, never heard of an accident - have seen one or two rather alarmed students.

How old? I passed my first PPL in 1993, and remember having to demonstrate a spiral dive entry and recovery for that. I didn't get the impression that it was at-all new.

G

[BEagle]

...pull and roll to recover... From a spiral descent?

:hmm:

[MrAverage]

Current teaching from the FIE I am familiar with is Power (to idle in the example given), Roll, Pitch. Same for any unusual attitude.


I should like to know if he's wrong...............

[dobbin1]

I teach throttle to idle, roll wings level, bring nose up to the horizon, reapply power at normal cruise speed.

[nick14]

Nose low (SEP) should always start with power to idle, roll in the shortest direction to wings level then apply back pressure to recover from the descent. Similarly to a Jet recovery except you don't tend to touch the thrust in the jet.

Pulling then rolling encourages people to do both which we all know is dangerous!

[S-Works]

Roll and push to enter, pull and roll to recover, watch the g.


One of the minor problems with the CRI course is the lack of depth. A great rating but with obvious limitations.

Funnily enough I have been teaching this skill all day as I have two CPL students on the go. Others have already stated correct technique.

[Genghis the Engineer]

One of the minor problems with the CRI course is the lack of depth. A great rating but with obvious limitations.

Funnily enough I have been teaching this skill all day as I have two CPL students on the go. Others have already stated correct technique.

Wasn't covered at-all on my CRI course, was covered on microlight PPL, wasn't covered on my JAR-PPL, was covered on my CPL.

And yes, close throttle, roll, pitch - good point, well made. P-R-P as I did drill into myself once upon a time.


Double checking the books I happen to have on the shelf, yes all say power/roll/pitch. I'm not going to argue my corner - I type slightly faster than I engage brain some days. I make less mistakes in the cockpit I hope !


I stand by the other point - straightforward, and I don't believe has ever caused an accident?

G

[Duchess_Driver]

Wasn't covered at-all on my CRI course,

No, I don't think it was.

However, back on theme (we can argue about the CRI Course later!)...

In Ireland I teach to some extreme attitudes.... and was shocked when one of my students told me (after test) that I was a pussycat in comparison to the examiner who gave the student some harsh attitudes that I didn't dare push the aircraft to.

Recovery is always the same - power to idle, check ASI for caution range, roll then pitch. In these instances I am happy for the student to recover to a straight and level attitude and never had an examiner want anything other than that.

[hugh flung_dung]

When recovering from a spiral dive the airspeed is usually above trim speed so, as the wings are rolled level, there is a strong tendency to pitch up which many studes are reluctant to resist. I always briefed the V-n diagram, Vne/Vd, and the dangers of a rolling pull and then insisted on a sequence of: power off, roll to wings level (resist the pitch), then smoothly raise the nose without overstress. IMnsHO it's much better to do this, spinning and sideslip stalls in an aerobatic aircraft because then the stude can be allowed a bit more latitude.

GtE - the sequence is very important because of the potential for overstress on the up-going wing, as I know you know ;-)

DD - why do you check the ASI during a spiral dive recovery? - by definition the speed is high and rising so I can't see what benefit a glance at the ASI might bring.

HFD

[BigEndBob]

I teach and want to see on test; power off, unload, roll wings level, pull to level, wait for cruise speed and set cruise power.
Approach to Vne doesn't necessarily mean reach Vne!

[Genghis the Engineer]

GtE - the sequence is very important because of the potential for overstress on the up-going wing, as I know you know ;-)



I am just pleading insanity over that incorrect couple of words.

Unloading is a good point by Bob, and is jet teaching. Not normally taught in SEP. Why not?

G

[BEagle]

The mantra 'speed, 'g', roll, pitch' works for pretty well any unusual attitude recovery:

Speed - if high and increasing, close throttle to idle. If low and decreasing, select full power (and no, the aircraft won't 'torque roll'!). If constant, leave throttle alone.

'g' - select +1g (important if IMC with a Turn and Slip and no Attitude Indicator)

Roll - in IMC, about half aileron until turn needle passes neutral, then centralise. In VMC, roll to wings level.

Pitch - in IMC, to oppose the altimeter movement. In VMC to the cruise attitude.

....and breathe!

[Genghis the Engineer]

In jets, there is certainly a body of thought that around 0.5g is better than 1g; the obvious disadvantage of that is that the aeroplane will increase speed more rapidly. The obvious advantage is the reduced airframe loaing.

G

[Duchess_Driver]

DD - why do you check the ASI during a spiral dive recovery? - by definition the speed is high and rising so I can't see what benefit a glance at the ASI might bring.


I get the students to do it, especially early on in their training as a reminder NOT to go 'ALL OUT' on the controls and over stress the frame. A minor thing, but I've seen a few get 'panicked' by the increasing attitude/speed and roll and pull "come what may". That little check just gives a more reasoned and cautious response by the student.

[dirkdj]

I have trained spiral dive recovery as taught by the American Bonanza Society. The Bonanza has a natural tendency to end up in a spiral dive if left to itself. During BPPP training it was stressed that once the wings are level, you most probably will have to PUSH on the yoke since you are so far above trim speed. The aircraft will pitch up by itself and if left unchecked could actually do a nice 4G pull into the first half of a loop. A slow draggy trainer may be more forgiving but on a clean retractable the speed builds quickly.

[Big Pistons Forever]

One of the things that IMO is a problem in flight training is the tendency to teach the exercise as a stand alone lesson.

It doesn't matter if you do a textbook recovery if you are in a spiral dive you have fecked up as a pilot at a pretty basic level. Good pilots will recognize the fact that the aircraft is developing a flight path that will result in a spiral dive and fix the issue before a full on spiral dive recovery is required.

Therefore training should emphasize those early indicators of the fact that things are moving in the wrong direction, chief among them the importance of not letting uncommandrd nose down attitudes develop when the aircraft is in a significant banked attitude.

I always teach the spiral dive lesson as continuation of the steep turn exercise not as a stand alone air exercise.

As for going to VNE on the exercise :suspect:.....well I think that is just plain silly. The point of the exercise is to teach how to recognize, avoid and recover. Holding the aircraft in a spiral dive until the aircraft has accelerated that much makes no sense to me.

[dirkdj]

If someone would be stupid enough to allow a practice spiral dive up to Vne, if the student would have the reflex to pitch up by pulling on the yoke, how much Gs could be pulled? Will the wings or the tail stay on very long?

This practice seems highly improper to me.

Here are the notes from the Instructor's In-Flight Guide for the Bonanza BPPP program:

Spiral Demonstration (Bonanza)

- Enter at 90-100 KIAS, trimmed for level flight
- Roll to 50-60° then hands off
- Recover at Va. Expect +2G's on recovery.

Expanded Notes:

- Need 40 KIAS increase to demonstrate trim pressure
- Let spiral dive develop fully
- Recover at Va (roll wings level and note forward pressure required
- Discuss results if entered at cruise speed BUT DO NOT DO IT!


Hundreds of pilots have been succesfully trained like this. Once seen and felt, it is evident that the correct recovery is by pushing to limit the 'return-to-trimspeed pitchup' by the airframe.

[Tarq57]

I have trained spiral dive recovery as taught by the American Bonanza Society. The Bonanza has a natural tendency to end up in a spiral dive if left to itself. During BPPP training it was stressed that once the wings are level, you most probably will have to PUSH on the yoke since you are so far above trim speed. The aircraft will pitch up by itself and if left unchecked could actually do a nice 4G pull into the first half of a loop. A slow draggy trainer may be more forgiving but on a clean retractable the speed builds quickly.
This.

In any spiral dive I've been in, where the airspeed is well above the trim speed (and it usually is), there is a strong pitch-up tendency as the wings are approaching level. If the airspeed is redlined, or approaching that point, I would see it as critical to not over- G the airframe.

Not experienced this in a Bonanza, but certainly have in a range of Cherokees and Cessnas, an Airtourer, a Beagle, and a baby Bonanza (Sundowner.)

[nick14]

0.5 G in jets is all very well and good but when was the last time you saw one in a modern multi engine jet transport?

The most critical difference between the jet and piston world is that the thrust/power is great almost in the opposite sense (mainly referenced by 737 but equally applicable to any jet with under slung engines).

Nose low, leave the thrust where it is roll and pitch. Nose high you may even need to reduce thrust to get the nose down, think about the Thomson BOH incident.

[Pom pom]

*** stoopid question alert ***

I'm not an instructor, so please forgive me! When recovering from a spiral dive, under the hood, maybe limited panel, I've never understood why it's not a good idea to use the kinetic energy created to recover back to the original (or as close as) altitude one was at when the departure from s&l occurred. Isn't there a chance that the unintended dive put one below msa, and that to recover just to s&l at the lower altitude, perhaps in cloud, is throwing away valuable time/distance to remain above an obstruction?

[Cobalt]

Because straight and level it is the easiest attitude to recover to, and if you try to get straight into a climb there is considerable risk that you overpitch and end up in a stall.


When you are pulling out of the dive, at some point the speed will start to drop and the altimeter will stop unwinding, both indicating that you have found the horizon, so you have two instruments telling you that you got it right. The exact point is also quite easy to see - it is when the respective needle stops and starts going the other way.


In the climb, you only have the airspeed indicator, and you are aiming for a specific climb speed. You need to anticipate the point at which to relax the backpressure or you will undershoot the target speed. The inertia of the nose swinging up is not helping, either. Best case, you catch it before the stall and sort it out after a couple of oscillations. Worst case, you are halfway around the loop, flop out to one side and have to wait to do it all over again.... in IMC.... on limited panel. Well, at least the turn coordinator does not topple, let's hope the spin is upright and not inverted...

[Pull what]

I get the students to do it, especially early on in their training as a reminder NOT to go 'ALL OUT' on the controls and over stress the frame. A minor thing, but I've seen a few get 'panicked' by the increasing attitude/speed and roll and pull "come what may". That little check just gives a more reasoned and cautious response by the student.

Check the speed! Check the speed and do what? Hope perhaps that they have read about VMO? ( which it seems you and others have forgotten to mention).

Consideration of VMO is the first objective in recovery from a high speed upset and recovery

[Piltdown Man]

Speed - High = Close throttle, Low = Full power
g - Get it to 1
Roll - Roll to the nearest horizon (or to stop T/C showing turn)
Pitch - Pitch to normal attitude (or to stop ASI changing)

PM