Mark-On-Top Call - P-8020077

INSTRUMENTS FLIGHT PLANNING

CHAPTER FOUR

If you predicted arrival at MAI at 00+00, then your TWO-MINUTE PRIOR Call commences at

58+00. It is a good idea to keep a scan on your DME and check it at 58+00 to ensure that your

call is timely.

403.

MARK-ON-TOP CALL

Now that you and the pilot have a two-minute warning, let us look at the MARK-ON-TOP report

the pilot requires at each checkpoint or NAVAID. Your MARK-ON-TOP report is required at

all NAVAIDs during an IFR flight. When navigating to a TACAN station, MARK-ON-TOP is

at minimum DME for direct navigation or when the TACAN needle passes either 90 benchmark

when leading turns. Point-to-point navigation uses the closest point of approach.

There are five bits of information the pilot requires at the MARK-ON-TOP point:

Turn right/left to a heading

Time

Place

Fuel quantity

NAVAID

Analysis:

Item (1) requires you to tell the pilot to turn left or right to a heading. That heading is the

heading to get the aircraft on the outbound course. In choosing a heading, you must take turn

radius, winds, and navigational procedures into account.

Item (2) is simply the actual clock time you pass on top.

Item (3) requires you to name the point you are passing.

Item (4) is the fuel quantity you predicted for the MARK-ON-TOP from your TWO-MINUTE

PRIOR figures.

Item (5) is the NAVAID you use for your next leg. If turning onto an airway, the NAVAID

remains the same, if flying direct the NAVAID changes.

A typical MARK-ON-TOP Call sounds like this:

"Turn right 138o, time 00+00, Marianna, fuel quantity 600 lbs, NAVAID remains the same."

Note that we turned the aircraft to 138 to fly a course of 141. A turn of 51 is involved

requiring a lead point to roll wings-level on course. The formula for a 90 turn is of 1% of the

aircraft's GS plus minimum DME. However, since the turn is only 51 we must adjust the lead

point by some amount in an attempt to roll wings-level on course. One-half of 1% of 210 kts =

1.0 DME, but we adjust this to .5 DME (as 51 is roughly one-half of 90). Now .5 DME + 2.5

TWO-MINUTE PRIOR, MARK-ON-TOP AND WINGS LEVEL CALLS

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