The Six Minute Rule: Crosswind

T-6A NAVIGATION

CHAPTER FIVE

508.

THE SIX MINUTE RULE: CROSSWIND

Let's take a look at some special cases of the equations discussed so far. What if the time interval

flown was six minutes? First, let's look at crosswind for a speed of 180knots:

Distance off course (NM)

60 min

= Crosswind (knots)

1 hr

Reducing the terms, we find that for five minute intervals crosswind equals:

Distance off course in miles X

= Crosswind (knots)

Example

After flying 6 minutes without a heading change, the aircraft marked abeam a checkpoint at 1

NM off course to the left. Using the 6 minute rule, what is the crosswind?

(1 NM off course) X 10 = 10 knots crosswind from the right

For our purposes, we can use the above equation for time intervals between 5 and 7 minutes

without sacrificing a significant amount of accuracy. You may want to check other intervals as

well. What would the equation look like if the time interval ten minutes? What about three?

509.

THE SIX MINUTE RULE: HEAD/TAIL WIND

Now let's look at our head/tail wind equations. For five-minute intervals we have:

Time off updated time (sec) X

Head/Tailwind (knots)

Which becomes:

Head/Tailwind (knots)

Time off updated time (sec)

For computing head/tail wind components over 5 to 7 minute intervals, simply use half of the

time off in seconds. Again, it may be helpful to check other intervals as well. Remember the six

minute rules are approximations when not used at exactly six minute intervals.

Your results using a five or seven minute interval are reasonably accurate, but requires

considerably more mental math. To improve your accuracy when using these techniques, round

up when using intervals closer to five minutes and round down if closer to seven minutes.

Additionally, refine your computations as more information becomes available along the low-

level route and always round to the closest 5 knots increment.

FLIGHT PROCEDURES

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