Mental Maths!!

[boeingbus2002]

Has anyone got any tips to improve mental maths ability?
I know it would help speed things up calculating things for diversions etc. and this isnt too bad on the ground, but in the air my brain seems to go dead...when it comes to calculations and flying!
Cheers!:rolleyes:

[somewhatconcerned]

You are missing the point, yes i know mental maths or what ever you choose to call it does help but you need to learn to cheat. Near enough is good enough and all that. During your trainning you will come accross many rules of thumb listen to those who tell you them and learn.
I was pretty darn good at mental arithmetic but with all the noise and flak it all goes out of the window. An E6b (crappy5) bezel on your watch can help during those CRAFT moments (can't remember a Firkin Thing).
Do a google search on 'rules of thumb' you should find loads of helpful stuffwww.google.com (http://)
Oh and RELAX:D

[FlyingForFun]

As you go around the supermarket, try to keep a tally of how much the bill will come to. Not exactly, just roughly. E.g. "Two item, about 70p each, one item, about £1.50, so that's a little under £3. Next item is a little over £1, so the total's about £4...." you get the idea. See if you can get the total right to within, say 5%.

FFF
---------

[Edited because my mental maths was wrong! :rolleyes: ]

[SpinSpinSugar]

.... and working out what the +/- 5% margin is with your mental arithmetic won't do you any harm either .... :D

[feetnkneestogether]

Try this one......

Whilst driving on the motorway I often look at the signs giving distances to the next town.
I look at the speedo and do a quick mental calc of how long it will take us to get there, (or mile per minute).
Make a note of the time and thus your ETA.

Adjust the time if the motorway slows and update your ETA.

On arrival see how far out you were.

It passes the time anyway.......!

[monkeyboy]

Boeing, I too had major problems with mental maths in the cockpit - especially with diversions - until a non-pilot firend taught me this trick. Trust me, you'll love this!

1) Work out your distance

2) Times the distance by 6

3) Divide the figure in 2 by your groundspeed (but you can cheat a little here and chop off the last figure of the GS (divide by 10) and then use that to divide by.


Here's an example:

1) Distance = 20nm

2) 20 x 6 = 120

3) (Let's assume our GS is 110kts.) To make it easier to work out we divide the GS by 10 at all times. 120 (figure gained in 2) divided by 11 (GS divided by 10) equals roughly 11 which equals 11 mins.

Given that you're allowed 1 min either side during your PPL skill test this trick should do you proud!

Try it on your CRP1/5 just to make sure.


PS: Any errors are purely due to the 3 pints of the black stuff I've just consumed.

MB :)

[Slasher]

Dont sweat it too much BB2002. Its all a question of proportionality and ratio really. If this is to this, then that is to [?]

For example say its presentley 0414Z and Im doing a g.speed of 472 knots (449 true) and burning 2.73T of fuel per hour, 213 miles out from departure airport. By the gages I have 5430kg of fuel on board. Should I have to turn back RIGHT NOW to my departure airport, what will be my ETA and FOB on arrival?

Itll take only 2 minutes tops to calculate!

1. NOW Ill have a 20 head-wind so Ill have a return GS of 430 knots. Thats about 7nm a minute (430/60)-(mentaly 6 x 7 = 42). If I have 213nm to fly I have 30 1/2 minutes (213/7) - (mentaly 3 x 7 = 21). Add in the 180 deg turn of two minutes and I come up with an ETI of around 33 mins. Throw in an extra minute for TAS reduction during the descent and I get 34 minutes. But Im doing 10nm per hour faster (430 knots not the 420 which I used as 7nm a minute) so in 30 odd minutes Ill do about 5nm more. So Ill knock off a minute and call it an ETI of 33 minutes. So ETA is 0414 + 33 = 0447Z.

2. 2.73T an hour is about 45 kg a minute (2.73/60)- (mentaly 6 x 4 = 24. 27-24=3, which is a half of 6). In 33 minutes Ill burn about (30min x 40 =1200kg, + 3min x 45=135kg) 1335kg calling it 1400kg to conservativley allow for the tiney extra of fuel flow over the 45kg a minute rate I used. Maybe Ill knock off 100 kg to allow for the flight idle descent so Im looking at 1300kg if I want to be super-accurate. So 5430kg is by now about 5400, so 5400kg minus 1300kg = 4100kg overhead departure airport.

See its not too hard huh? Just a matter of ratio and proportion wether its a 737 or Cessna 172. It comes easier with experience and exposure. But if in doubt ALWAYS carry your Jep or Kane whizzwheel and know how to use it. Of course you can use any of the latest electronic calculating toys but whizwheels and brains dont get flat batterys!

Other stuff like calculating drift from winds, how far from an NDB to start the turn from a 90 deg intercept for the next leg from overhead etc is generaly picked up by reading and asking on BBs like Tech Log etc.

Hope this helps.

[Flaps 10]

Buy a knightson, it will sort your diversions out in no time and save conting on your fingers with your tongue hanging out! they are available in 100/120kts cruising speeds. Used them for my CPL, theres no other way.

However, if you are still keen on the mental arithmatic, then i used to play with the numbers on car registrations as they pass me (got a slow car!). Beware, keep a safe distance between you and the car infront as them in blue wont be impressed with your excuse!!

good luck:p

[boeingbus2002]

Well Rules of Thumb was the kind of thing i was looking for! But all valuable tips.

Any more info on that Knightson thing? Where can i acquire one, price, usefulness etc?

:rolleyes: