Rules of Thumb
 

Hi fellow aviators I would like to know all your rule of thumb info. It seems that whilst training there is a lot of maths etc, which then you have to use the wiz wheel for. Only to find out when talking to more experienced pilots there is a rule of thumb for that which could be easier.Can we all share our Rule of Thumb info? no matter how small it is just jot it down.

Crosswind - the simple (on final) mental calculation

Split the watch face into 4 quarters - 1 to 3 = 1/4, 3 to 6 = 1/2, over 6 = full crosswind

Wind 10-30 deg off runway is in the first 1/4 - take 1/4 of wind as crosswind
Wind 30-60 deg off runway is in the second quarter - take 1/2 of wind as crosswind
Wind 60 deg + take all of wind as crosswind

From your knuckle to the tip - how long is your thumb?

On an average spread - how wide is your hand from thumb to little finger?

It helps with diversion planning whilst in the air.

Crosswind
 

Even simpler, and more accurate, than the previous reply, take the number of degrees the wind is off the runway heading, divide by 10, then divide by 6. The crosswind is that fraction of the wind strength.

So if Rwy is 020 and wind is 040/12k, then wind is 20 degrees right of rwy heading. So 2/6 of 12k = 4kts xwind from the right

Example: Same rwy and wind stength but the wind direction changes
Wind 020 -diff = 0, so 0/6 = no crosswind
Wind 030 - diff = 10, so 1/6 = 2kts
Wind 040 - diff = 20, so 2/6 = 1/3 = 4kts
Wind 050 - diff = 30, so 3/6 = 1/2 = 6kts
Wind 060 - diff = 40, so 4/6 = 2/3 = 8kts
Wind 070 - diff = 50, so 5/6 = 10kts
Wind 080 - diff = 60, 6/6 = 12kts Full crosswind component.

If you think it looks dodgy, it probably is!

That goes to anything from paperwork to maintenance, to the state of the aircraft to the weather etc.

Chance of survival is inversly proportional to angle of arrival

RULES OF THUMB

Dont get your thumb in the way when hammering in nails :=

Another one? for your descent point multiply your altitude by 3 ie 30,000 just take the 30x 3= 90 miles or 9000 feet 9 x 3 = 27 miles out.:)

Pace

To obtain a three degree glideslope:

- Altitude in 1000' of feet times three is the distance to descend.
- Groundspeed in knots times five is the vertical speed required.

beatnik,

dangerous one yours, a wind that is 30 deg off runway heading simply gives a crosswind component of half the wind speed. Your example gives a 2 kt crosswind when it should be 6. Mathematically it is the sin of the angle multiplied by the windspeed. Rules of thumb work but not this one.

Stick with the clock face and you can't go wrong. Failing that if it feels to strong it probably is.

In feet, one would hope :eek:

trex, you misread the table, Wind 30 on RWY 20 is 10 degrees off runway heading (not 30) - hence beatnick's result of 2 kts x-wind component.

beatnik -

Thanks for that one, that's extremely useful! :ok:

edit - although wouldn't use it above about 50 degrees as it becomes very inaccurate, but up to that, very close to the sine values!

Actually feet per minute.

Above 50 degrees you use the full wind strength for the x-wind component. That's actually very close to the sine values as well. In fact, you'll find that the inaccuracies of this method are less than the inaccuracies caused by the wind being variable, particularly in strong winds where it matters most.

Refer to post #6...

Also:

Nothing ever happens fast enough in aviation, unless something is going wrong...

Cheers Backpacker, never considered an x-wind safety factor, unlike tailwinds and headwinds. Learn something new every day :ok:

Rule of thumb
 

Used to be the max thickness of branch you could legally beat the missus with!

Fuel weight in KGS = 75% the volume...... not exactly but OK for calculations..
(eg) 100 litres fuel = 75KGS
80 litres fuel = 60KGS

mm flynn, thanks for that, sorry Beatnik I stand corrected.

One I use on almost every flight: Dependence on weight for approach speed, best glide speed, VX, VY, VA: The percentage change in speed is half the percentage change in weight.


Penetration speed: When gliding with a head wind, increase gliding speed by a quarter of the wind speed. When gliding with a tail wind, glide slightly slower, but never slower than the minimum sink speed.


IAS -> TAS: Two percent per 1,000 ft.


Crosswind correction: 1 knot crosswind per 1 degree correction, per 60 kts GS. E.g., 10 kt crosswind component at 120 kts GS requires 5 degrees correction.

Where would one use that rule?