Jump to content

Help! Aviation Weather, Radio Work, Ground Speed Checks/etas


Recommended Posts

Honestly, I'm crap at math too. I forced myself to sit down at night during my commercail training and do mental math till I wanted to cry, then I did some more. Finally something clicked, as it does for everyone, and it all made sense.


Biggest rule I was taught was something called the Rule of 60. When it comes to any mental math in aviation, the number 60 is your best friend. As Dimit hinted at, it all revolves around the minutes in an hour and how they relate to your ground speed checks. And as it's your ground speed check, you choose the minute value you want. Use minutes for a speed check ones that will divide into 60 evenly.... like 2, 3, 4, 5, 6, 10, 12.


Three-minute speed checks seem to work best, and are a snap to figure in your head with some practice. Three minutes goes into 60 minutes, twenty times right. So multiply your distance flown by 20 to get your ground speed. Easy eh!

Flew 3 nm = 60 kts

Flew 4 nm = 80 kts

Flew 5 nm = 100 kts

Flew 3.5 nm = 70 kts

etc etc etc.


For more complex calculations, just take your time untill you get faster at them. When buzzing about solo give yourself questions in the air. Doing this crap on the ground is one thing, but doing it in the machine while scanning for traffic, using both hands to fly and somehow read a map, listen/talk on the radio, bla bla bla.... it gets overwhelming very fast. This is why you need to get lightning fast and accurate at this type of mental math.


"You go 6 miles in 4 minutes. Your R22 burns about 8 gal/hour. At this rate can you divert to a hillside 60 nm away with your remaining 10 gals? Are you legal?" Break it down like this;


-Okay a 4 minute run... multiply the distance (6) by 15. So I'm doing 90 kts.

-Going 90nm in one hour. My diversion is 60nm away. 60 is 2/3's of 90nm/hour.

2/3's of an hour is 40 minutes, so it will take me 40 minutes to get to my diversion.

-My heli burns 8 Gal of fuel/hour, and I have 10 Gal in the tank right now. In 40 minutes I'll burn a little over 5 Gal, but round up to 6 Gal for safety.

-Yes I have fuel to reach my diversion and still be legal.


By the time you finish your commercial training you'll be able to do that kinda stuff in your head faster than you can read it here. Just keep at it.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...