Spiral

Spiral Dive

A spiral dive is a steep descending turn with the aircraft in an excessively nose-down attitude and with the airspeed increasing rapidly.

Objectives

  • The recognition of the conditions which could lead to a spiral dive.
  • The recognition of the spiral dive.
  • The correct recovery action.

Why ?

  • Spirals are probably responsible for more deaths than the spin.
  • If you fly into cloud without the training and the instruments to fly blind, you will enter a spiral dive within 178 seconds!
  • Spiral can overstress airplane and make structural damage.

Link

  • Descent.
  • Steep turn.
  • Spin.

Review Questions

  • What is happening if the airspeed is Increasing in spin?
  • Give the procedure to enter a spin.
  • Give the procedure to recover from a spin.

Spiral: basic theory

  • A spiral occurs in a steep descending turn.
    • Airspeed increasing rapidly.
    • Excessively nose-down attitude.
  • Aircraft speed limitations can be rapidly exceeded in a spiral dive.
Causes of spiral
  • During a spin it is possible to become temporarily disoriented, so that what appears to be a spin is actually a spiral, under these conditions, always remember that the main difference between the two manoeuvres is airspeed.
  • In steep turn if you let the nose down the airspeed will increase and the spiral occurs.
  • If a spin entry is not completed properly aircraft will not achieve autorotation and will enter a spiral dive exemple:
    • Attempting to force a spin before a stall.
    • Relaxing elevators once in a spin.
    • Poor spin recovery.
Spiral
  • The speed is increasing rapidly.
  • Altitude is lost at an increasing rate.
  • The « g » force is increasing.
  • * Wings are not stalled
Spin
  • The airspeed is low and oscillates up and down.
  • The rate of descent (height loss) is steady..
  • The « g » force remain low.
  • * Wings are stalled

Instrument Indications

Attitude Indicator (AI):

  • Nose down.
  • May be unreliable.

Heading Indicator (HI) :

  • Changing heading.
  • May be unreliable.

Air Speed Indicator (ASI):

  • Rapidly increasing.

Alitmeter (ALT):

  • Rapidly decreasing.

Vertical Speed Indactor (VSI):

  • Show a rapid descent.

Turn-coordinator:

  • Full scale deflection in the direction of spiral.

Spiral Recovery

  • Close the throttle immediately.
  • Roll the wing level (avoid rolling and pulling up at the same time).
  • Ease out of dive by pulling up,
  • Apply power only after the airspeed has decreased to within normal range and positive rate of climb.
  • Don’t recover too abruptly, that could result in an excessive load factor, with a danger of a pilot black-out, structural damage, or a high-speed stall.

Review questions

  • What are 3 indications you are in a spiral dive?
  • What is the main difference between a spin and a spiral ?
  • When can you add power during the recovery?
  • How do you recover from a spiral dive ?