Determine ETA at MCN

INSTRUMENTS FLIGHT PLANNING

CHAPTER THREE

At 0900, you notice during your scan that the No. 2 needle is spinning and the DME is not

functioning. There is no station IDENT. The last DME readout you had was 50 DME. Now the

pilot wants to know when to turn.

Your action is:

Determine ETA at MCN

GS = 360 kts (6 NM/min)

Distance to turnpoint = 50

Therefore:

ETE = 8 min

ETA = 0908

Heading is maintaining course so no change is necessary.

What you have just done is perform DR. Based on all the information available, you have

predicted when the aircraft will mark a turnpoint. There is no physical indication that you are at

MCN, only your ETA will provide you an estimate.

As long as you have a GS, you can predict where the aircraft is over any distance.

Continuing the example, your route of flight has the aircraft MARK-ON-TOP MCN, then

proceed to Alma (AMG) via J45. The pilot needs to know what heading to fly and what the ETA

is to AMG (Figure 3-3).

The simple thing would be turn to 139, the outbound course from MCN, at 0908. This does not

account for any wind; therefore, the aircraft does not maintain course.

It is absolutely critical that the wind is calculated and accounted for, before making the turn at

MCN.

Based on:

TAS = 300 kts

GS = 360 kts

CRAB = 5 right (083 for 078)

Plotting on the CR-2 yields a wind vector of 235/65 kts.

SITUATIONAL AWARENESS

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