I2002"BI 2"

Last updated: 3 June, 2008 16:46 by Bryan Weatherup
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IND-350 Course Deviation Indicator (CDI)

Each cockpit station has a CDI to indicate the aircraft’s actual course of flight relative to a course selected with the OBS knob. The CDI in each cockpit is individually set to a desired course heading with the respective OBS selector to or from the selected NAVAID. The NAVAID for both CDIs is determined by the cockpit having avionics command. The CDI needle of the cockpit selecting a center vertical position will deflect left or right of center if the flight course drifts. The VOR-TACAN selector switch and the OBS selector knob on one cockpit CDI do not affect operation of the other CDI.

The amount of drift will be indicated in degrees of course deviation to the right or left of centered alignment, 2 degrees per mark). To correct for a course deviation drift, proper sensing is determined and the aircraft is turned toward the direction of the needle deflection. When course alignment is reestablished, the CDI needle will be at the center vertical position for the cockpit from which correction is being made.

The TO/FROM indicators in the CDI will indicate whether the course selected by the OBS knob will take the aircraft to or from the selected NAVAID. The VOR-TACAN switch above each NACWS CDU selects which navigation system control the respective indicator. A red off flag will appear in the CDI anytime the respective NAVAID selected is not strong enough to lock on and indicates an unreliable signal.

FUEL PRESS light (low fuel pressure light)

A loss of boosted fuel pressure to the primary fuel pump, as sensed by the fuel pressure transmitter that is integral with the firewall fuel filter, is indicated by the steady illumination of the yellow FUEL PRESS light on the annunciator panel and steady flashing of the MASTER CAUTION light on the instrument panel. Activating the electric standby boost pump will restore boosted fuel pressure and extinguish both the MASER CAUTION and FUEL PRESS lights. The FUEL PRESS indicator light circuit breaker placarded FUEL PRESS is on the circuit breaker panel in the forward cockpit.

Engine-driven or electric (standby) fuel boost pump failure

The engine-driven primary fuel pump will sustain engine operation after failure of the engine-driven boost pump and the electric-driven standby fuel pump. In normal operations, the standby fuel pump is OFF, so illumination of the FUEL PRESS annunciator and MASTER CAUTION light indicates probable failure of the engine-driven boost pump. Illumination of the FUEL PRESS annunciator and MASTER CAUTION light may also indicate failure of the engine oil scavenge system. If the engine oil scavenge system has failed, engine failure because of cessation of lubricating oil circulation will occur, and the pilot should be prepared to land as soon as possible.

FUEL PRESS and MASTER CAUTION annunciator illuminated

  2. Standby fuel pump switch - ON

    If lights remain illuminated:
  3. Descend below 15,000 feet, and avoid high power settings.

    NOTE - Log time of illuminated FUEL PRESS light as solitary operation of the engine-driven primary pump. The max is 10 hours.

(Direct to VOR / TACAN - see below)

Oil system failure - Fluctuating (> +/- 5 PSI), Low/high pressure (<65 PSI @ >75% N1, >80 PSI), High temperature (>100° C)

  1. PEL - EXECUTE (850 ft-lb max & avoid unnecessary PCL movements)
    If engine malfunction or engine failure occurs:

NOTE - Because of the design and installation of the oil pressure transmitting and indicating system, minor fluctuations of oil pressure may be noted by the pilot with a normally functioning engine oil system. A vibrating needle or minor fluctuations of pressure with a steady mean, where extremes of needle movement remain within the normal range and do not exceed +5 psi, are acceptable when no secondary indications of engine malfunction are observed.

Fuel control rollback
Prop RPM
80-100 PPH

Reduced fuel flow (rollback) is typical of a fuel control unit pneumatic sensing system malfunction. If engine will not respond to PCL movements and ITT and N1 indicate the engine is running at a very low power settings, advance the EPL in an attempt to regain control of engine power by use of the manual fuel control system. N1 40-62% - indicating a "rollback" (fuel control unit stuck at minimum flow), proceed as follows:

  1. Condition lever - FULL INCREASE RPM

    NOTE - When using EPL maintain N1 above 65% to improve engine response and ensure generator stays online.

    If the resultant power available is insufficient to execute a PEL:
  4. ENGINE FAILURE procedure - EXECUTE.

    WARNING - When the engine is so underpowered that high rates of descent occur, any delay in feathering the propeller may result in insufficient altitude to reach a suitable landing site. It is not recommended to delay feathering the prop in the landing configuration below landing pattern altitude.

    If sufficient power is restored:
  5. PCL - IDLE

    CAUTION - Use of BETA is not recommended when performing a landing using the manual fuel control system. If the use of BETA is required, ensure the EPL is in the IDLE range or DISCONNECT before selecting BETA with the PCL.

New Maneuvers for this event:

Constant rate turns (CRT)

During normal airways flight in the navigation stage of your training, all turns will generally be done at a specified rate, either standard or one-half standard-rate turns. The standard-rate of turn is 3° per second. At 3° per second, a turn of 180° will take 1 minute and a 360 degree turn will take two minutes. The figure below is a chart showing the AOB necessary to produce a 3 degree per second turn at various airspeeds and altitudes. From the chart you can see that an aircraft operating at high speeds requires a steep AOB to produce a 3 degree per second turn. Steep turns are more difficult to fly than shallow turns, since they result in heavy load factors; for example, a 60 degree bank turn applies a two “G” force to the aircraft and pilot. To avoid these “G” forces, an FAA rule states, “use either a standard-rate turn (SRT) or 30 degree AOB whichever occurs first.


The turns are practiced initially in level flight, cross checking the nose with the VSI and altimeter and the wings on the turn needle. A one-needle-width deflection produces a ½ SRT and a two-needle-width deflection a full SRT. The performance of the turns will be checking on the RMI by checking for 30° in 10 seconds for a SRT. Since the AOB required to produce a constant-rate turn will vary with airspeed, we need some method of determining proper bank for a specific needle deflection. An accurate rule of thumb is to establish an AOB equal to 10% of the airspeed for a ½ SRT, i.e., at 150 KIAS, a 15 degree AOB should be initially established. Double the above value for bank necessary in a full SRT. However, use 30° maximum AOB while flying instruments. This 10% rule is valid only in balanced flight.


  1. Normal cruise on cardinal heading, clock on a 6 or 12, three second lead.
  2. Roll 10% airspeed (15° AOB), crosscheck scan of turn needle for one needle-width deflection & altimeter / VSI.
  3. When RMI is 30° past the cardinal heading, check 20 seconds elapsed. Repeat.
  4. Use 10-20° AOB max to catch up / slow down.
  5. Roll out of the desired heading, using 1/3 rule for constant AOB turns to gyro heading.
  6. IGO report

    NOTE - There are two valid reasons for checking the heading change against the clock rather than checking the time prior to referring to the heading.
    1. The instruments are arranged on the panel in groups. The attitude gyro, RMI, altimeter, and airspeed indicator are grouped together. Thus, while scanning the instruments, you do not have to shift you point of vision very far to check the RMI.
    2. Since the clock tells you nothing about the aircraft’s attitude, the time spent scanning is actually wasted. If the clock is checked only once every 20 seconds, rather than 4-5 times, you will be able to devote more time to the attitude instrument scan.
    3. Fixing turn: If larger corrections are made, the rate of correction will be too rapid and you bypass the heading.


  1. Slow cruise on cardinal heading, clock on a 6 or 12, three second lead.
  2. Roll 20% airspeed (24° AOB), crosscheck scan of turn needle for one needle-width deflection & altimeter / VSI.
  3. When RMI is 30° past the cardinal heading, check 10 seconds elapsed. Repeat.
  4. Use 15-30° AOB to catch up or slow the rate.
  5. Roll out of the desired heading, using 1/3 rule for constant AOB turns to gyro heading.
  6. IGO report

    NOTE - Transition from 150 KIAS to 120 KIAS (slow cruise configuration) by reducing power to 300 ft-lbs. Retrim.

    Common errors:

    1. Not using a 3 second lead.
    2. Not relying on the wing attitude instrument (turn needle) but trying to fly performance instruments. The turn needle is one of the most accurate instruments in the aircraft-believe it. Remember, the performance checks are only readable every 30°.
    3. Unbalanced flight.
    4. Over correcting AOB - never greater than 20° or less than 10° for a ½ SRT, never greater than 30 degree AOB or less than 15 AOB for a SRT.
    5. Improper nose attitude, losing altitude.

Constant rate climbs/descents (CRC/D)

Proficiency in performing climbs and descents at a definite vertical speed is very important in actual instrument flight. The vertical speed as well as airspeed must be controlled accurately during a precision GCA, ILS approach, instrument takeoff, etc. The standard rate for climbs and descents has been established at 500 fpm. However, since jet powered aircraft operate most efficiently at high altitudes, a higher rate of altitude change may be used by these aircraft, often as high as 4000 fpm. In this manual, we shall consider primarily descents and climbs at 1000 fpm. By using the same principles, the procedures for different rate of change may be derived.

A constant rate descent is in reality a constant airspeed descent, performed at an exact rate. In other words, attitude (airspeed) is the primary consideration and performance (rate) secondary. You learned in the previous section that nose attitude controls airspeed; now you will learn to maintain a constant airspeed and vary your rate of descent by use of power adjustment. Power controls rate of descent or climb.

Constant rate climbs and descents are performed in VPS configuration. They are started on a numbered heading using a 3 second lead prior to the clock’s second hand reaching a 6 or 12 to compensate for attitude change. The transitions, scan, power settings, and trim are the same as constant airspeed climbs and descents with the inclusion of the VSI and clock as additional performance indicators.

Basic steps:








In order to check the performance in a 1000 fpm descent, crosscheck the VSI and utilize checkpoints on the altimeter. For every 250 feet of altitude change, check the clock for 15 seconds of elapsed time or every 500 feet, 30 seconds of elapsed time.

If the descent becomes less than 1000 fpm, the rate of descent must be increased to a value greater than 1000 fpm to catch up with the time schedule. Be decreasing power and changing nose attitude (to maintain constant airspeed), you will increase the rate of descent. As soon as a checkpoint indicates that the aircraft is back on performance, attitude and power are again adjusted to maintain a 1000 fpm descent.

Let’s consider the corrections necessary for a rate of descent greater than the desired rate of 1000 fpm. If, for example, after descending 500 feet, only 25 seconds have elapsed, you are ahead of desired performance; power must be added and nose attitude adjusted up to slow the are of descent to less than 1000 fpm. As soon as the altitude change and time agree (500 feet at 30 seconds or 750 at 45 seconds), power and attitude must then be adjusted to a value between the initial setting, which resulted in a descent greater than 1000 fpm, and the first adjustment, which gave less than 1000 fpm descent.

NOTE - These power and attitude adjustments will continue to be made until altitude change and elapsed time coincide with a 1000 fpm descent. A constant rate cannot be maintained without a constant airspeed (130 KIAS), therefore prior to making power corrections, crosscheck airspeed.

The same principles apply for 1000 fpm climbs. A 1000 fpm climb will normally be achieved by using 850 ft-lbs torque. However, if you determine that the rate is insufficient and the addition of power to maximum allowable does not yield a 1000 fpm climb, maintain 130 KIAS, regardless of rate of climb.

Common errors:

  1. Starting the maneuver off altitude.
  2. Not using the 3 second lead. An incorrect or late transition will adversely affect your arriving at the first checkpoint at the correct time.
  3. Attempting to fly performance scan and neglecting airspeed. Positive performance checkpoints occur only once every 250 feet. The common tendency is to allow airspeed to remain off until a performance check indicates a deviation from the desired rate. If the airspeed is not 130 KIAS, the attitude is incorrect and the performance cannot possibly be proper. Make appropriate nose correction for airspeed when any deviation from 130 KIAS is indicated.
  4. Not re-trimming after making a correction. Remember, if you correct for airspeed or change power and ease the nose to maintain airspeed, you have “set” a new attitude. You must trim to hold it.
  5. Correcting the rate with nose movement: power controls rate. *
  6. Correcting airspeed with power: nose attitude controls airspeed. *
    * NOTE - Errors 5 and 6 are the most common.
  7. Over correcting for airspeed (equate nose movement to airspeed correction.

Direct to a VOR or TACAN

  1. TUNE and identify the station
    AVIONICS CONTROL. Ensure that you have avionics control
    ICS "Sir, taking avionics command now".
    Set the desired frequency or channel. If using TACAN, ensure you are tuned to the “X” band of the desired channel.
  2. IDENTIFY. Place the appropriate audio switch forward on the audio panel until the station is positively identified, then turn the switch off.
  3. TOGGLE. Ensure the appropriate NAVAID is selected using the toggle switch above the CDI/NACWS.
  4. TURN. Turn to place the single needle (VOR) or double needle (TACAN) under the heading index of the RMI.
  5. TWIST. Twist the omni bearing selector (OBS) knob in the CDI until the CDI centers with a white flag under “TO” in the TO/FROM indicator. The course under the index in the CDI with the CDI centered is the current course direct to the station.
  6. TALK. Report course to your instructor from the CDI. The maneuver is complete.

    NOTE - A TACAN station identification occurs only 35 seconds. If you do not know the MORSE identification, ask your instructor.

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