Vertical S-1 Pattern (S-1)

T-34C INSTRUMENTS

CHAPTER THREE

307.

VERTICAL S1 PATTERN (S1)

This pattern is flown in VPS and on any numbered heading. It consists of a 1000FPM

descent for 1000 feet, followed by a 1000 FPM climb for 1000 feet. This series of descents and

climbs is performed twice.

Begin the pattern with the descent using a threesecond lead prior to a 6 or 12. Perform the

same transition to a descent utilized in constantrate maneuvers. Performance checks are also

accomplished as in the constantrate maneuvers.

The transition from the descent to the climb is started three seconds prior to the end of the

descending minute or 50 feet prior to the end of the 1000 foot descent, whichever occurs first.

Add power toward approximately 850 ftlbs torque, while smoothly raising the nose toward the

climbing attitude of approximately 4 nose up; retrim for the 130 KIAS climbing attitude. As

power is added, backpressure must be simultaneously increased in order to prevent acceleration

and delay in climb rate.

NOTE

Because of the "lag" or inherent error in the altimeter, the altitude

will rarely stabilize exactly on a 1000 foot mark during the

transition. Therefore, a 1000foot altimeter mark on the 6 or 12 is

not an accurate checkpoint and should not be considered. The

transition is performed on the gyro, then reestablish the attitude

scan and finally, check performance at the first 250 feet in the

climb.

The transition from the climb to the descent is started three seconds prior to the end of the

climbing minute or 50 feet prior to reaching the original altitude, whichever occurs first. Reduce

the PCL (applying simultaneous, proportional left rudder pedal control pressure) to

approximately 250 ftlbs, while simultaneously lowering the nose to the descending attitude,

approximately 2 nose down. The second transition to a climb is accomplished exactly as was

the first.

In both climb and descent, the final checkpoint (250 feet remaining prior to transition) is

relatively inadequate for actual rate correction, as there is insufficient altitude remaining for a

correction to be effective. The value of these points is for determining whether to transition on

time or altitude. For example, if in the climb, the altimeter reads 250 feet to go (750 in the

climb) and ten seconds prior to a twelve (clock on ten), you are behind in the climb rate, and will

probably transition on the clock.

Complete the pattern by simultaneously reducing torque to VPS level flight power 50 feet

prior to reaching level off altitude, lowering the nose to the VPS level flight attitude. Stabilize in

VPS. Return to normal cruise when directed by your instructor by setting 1015 ftlbs (695 ITT

max). Two to three knots prior to 150 KIAS, set approximately 650700 ftlbs and retrim.

BASIC INSTRUMENTS FLIGHT PROCEDURES 3-19