Cross-unders

Introduction:

  • The purpose of a cross-under is to move the Wing from the parade position on one side of lead to the other
  • Cross unders may be used to:
    • Minimize Wing's exposure to sun
    • Area management
    • Breakup and rendezvous
    • Returning to the airfield (overhead maneuver)
  • The maneuver is performed slowly to control movement, and should be not be performed faster than a walking pace
  • There are two methods to perform this maneuver, the box, and the V

Cross-under Mechanics:

  • Throttles control nose-to-tail
  • Nose controls step-down
  • Angle of bank controls crossing rate
  • All corrections should be "3 part power corrections"

Cross-under Procedure:

  1. Cross-under Signal
    Cross-under Signal
  2. LEAD: Check the wingman is in position and the area is clear
  3. LEAD: Give the cross-under signal
    • The cross-under signal is a fist held vertically [Figure 1]
  4. WING: Acknowledge receipt of the signal with a head-nod
  5. WING: Simultaneously reduce the power slightly and pitch down to increase step-down

  6. Perform the Step-down:

    • Box Method:

      • Move straight back and down to achieve 10' of nose-to-tail and 15' of vertical separation
      • If the horizontal stabilizer is swept, you will be looking roughly down the leading edge
      • If the horizontal stabilizer is straight, you will be looking at the forward tip of the stabilizer moving toward the trailing edge of the wing
      • Add power to stabilize in position

    • V Method:

      • Move back at an angle while descending to establish 10' of nose-to-tail and 15' of vertical separation, established in column behind lead
      • Add power to stabilize in position

  7. Perform the Cross-under:

    • Box Method:

      • Simultaneously add power while increasing bank angle to move laterally to the same position, but on the other side of lead
      • Wing must achieve a controlled move to the other side of lead without disturbing the nose-to-tail clearance
        • Wings nose should never be under leads tail, EVER
        • Project yourself outside of leads wingtip to avoid driving too close
      • Add power to stabilize in the stepped-down position
      • Visual cues will remain the same as on the other side of lead

    • V Method:

      • N/A

  8. Return to Parade Position:

    • Box Method:

      • Simultaneously add power and increase pitch to maneuver back into parade position

    • V Method:

      • Complete the other side of the V, simultaneously adding power and increasing pitch to move back into parade position
  9. Cross-under Signal
    Cross-under Signal

Cross-under Common Errors:

  • Failure to observer/recognize the cross-under signal given by lead
  • Excessive control inputs
  • Not applying power early enough to prevent excessive drift aft of lead

Conclusion:

  • Formation maneuvers are unfamiliar to most in general aviation, requiring in-depth preflight briefing, communication, and practice
    • Do NOT treat these maneuvers haphazardly as the risk of mid-aid collision is clearly greater
    • Maneuvers should always be practiced with an instructor experienced in formation flight before attempting
  • Consider practicing maneuvers on a flight simulator to introduce yourself to maneuvers or knock off rust
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