Correcting pitch to hold level flight by instrument reference
Level flight = constant altitude. At fixed cruise power, any pitch away from level starts a climb or descent. Attitude indicator, altimeter, VSI, airspeed indicator all show it (TP 1102).
Cross-check (TP 1102):
| Instrument | Pitch info |
|---|---|
| Attitude indicator | Direct: raise or lower miniature aircraft against horizon bar |
| Altimeter, VSI | Indirect: climb or descent shown means not level, pitch correction needed |
- Miniature aircraft below horizon bar = nose below real horizon, regardless of physical sensation.
- Turbulence: steady indications hard, especially VSI (TP 1102, Instrument Flying: Level Flight).
Rate of change = size of error:
| Rate | Meaning | Response |
|---|---|---|
| Slow | Attitude already close | Small control inputs |
| Rapid | Large deviation | Bigger inputs, possibly power change too |
Correct in three steps (promptly, light control pressure):
- Stop the needle movement.
- Return to desired altitude.
- Stop that correction, settle onto desired level attitude.
- Small rate: small, smooth changes, then retrim (TP 1102, Level Flight).
Correction rate:
- Pitch for vertical speed about double the altitude error, e.g. 100 ft off = roughly 200 fpm.
- Bigger error, bigger return rate.
- Airspeed not above best rate-of-climb or rate-of-descent speed.
Trim:
- Trimmed aircraft needs minimum control use in smooth air (TP 1102, Straight-and-Level).
Trap: chasing the needle, matching every erratic VSI twitch with a new control input (especially in turbulence), builds oscillation; read the trend, not each flicker.
References
- TP 1102 Instrument Flying: Level Flight