Flying the Route - P-8690106

CHAPTER FIVE

T-6A NAVIGATION

Example

The time across a railroad bridge (preflight for 10+10, updated 10+0) is 9+55. Base airspeed is

180 knots, but compensated speed is 175 for the next leg. The previous turnpoint time was 6+50,

10 seconds early (which is why the updated time reflects 10 seconds early).

Time Analysis: "The checkpoint was at 9+55, preflight was 10+10, resulting in 15 seconds fast.

The aircraft is 15 seconds early. "Decrease airspeed to 155 knots (175-20) for 2 minutes and 30

seconds. Time in is 11+00. Time out is 13+30."

Update the ETA

During this step the time to anticipate subsequent points is updated. If you were less than 12

seconds off over the point, then modify any subsequent point along the next leg to reflect it. If

you initiated a time correction, leave the time unchanged if correction will be complete prior to

crossing the subsequent point. If the correction must be continued through the point, an

approximation of point time can be found by adding or subtracting 6 seconds for each minute

(for 20 knot corrections ) or 12 seconds per minute (for 40 knot corrections) that the correction

lasts past the point.

Example

30 sec late, compensated airspeed is 185, increase speed to 205, time in 15 + 00, time out 20 + 00

(5 min = 30 sec gain), Pt crossing at preflight 19 + 00. The updated time to cross the point would

be 19 + 06. This is so because 1 minute of correction remained.

Wind Consideration

During this final step of the wings level call, the wind is addressed. In the absence of significant

wind-induced deviations, leave the winds as preflighted, noting general direction and magnitude.

If the preflight wind is found to be inaccurate, update wind as required. Computation tools will

be explained later in the chapter.

Apply appropriate crab and airspeed adjustments to maintain 180 knots ground speed. For in-

flight adjustments use 2 degrees of crab for each 5 knots of crosswind. Increase/decrease the

compensated speed by the value of the headwind/tailwind component.

504. FLYING THE ROUTE

Flying a low-level route is a process of constantly discerning where you are (in relation to

mission course/time), correcting back to course/time, and assessing what caused the deviation. It

is through this simple process that the turnpoint procedures were developed. In particular "turn

analysis" and "time analysis" are steps to determine distance off mission parameters and initiate

corrections. Consequently, "Update ETA" and "Wind Considerations" fall in the regime of

5-20

FLIGHT PROCEDURES