Cockpit Aids.

[Maxflyer]

I am a student, not an instructor, so please forgive my intrusion into your forum. I know that in pre-flight planning I must use a whiz wheel, but I would like to know if during the skills test, when having to make my diversion, I am able to use a hand held flight computer to work out details such as ground speed, leg time etc? It seems to me that it should be ok considering it is far more accurate than my brain for estimating. Or is it that part of this exercise is to show the examiner that I am in the correct midset?

I would be grateful for clarity on this point.

Many thanks in anticipation.

TJ

[Homer_J]

If your going to divert form one place to another, then (in real life) theres probably a reason.
Lets say you want to go from liverpool to birmingham. If you file a flight plan, you will include a diversion, so in the pre flight planning you will already have an idea of your timings and headings to fly.
But on the test you'll probably divert from a turning point, to a church on the side of a hill thats covered by trees and is only visible from the opposite direction(i dont think my examiner liked me, or he was taking the piss, i was fairly sure of the surrounding terrain, but couldnt see the church, a quick 180 turn and i found it).

anyway to cut a small story short.......fly the plane, hell probably tell you the diversion a few mins before. so get the map out, draw a line, get the track and distance. (one of those rulers with the compass rose on is great). look at the wind arrow on your map, and if it was me, take an educated guess as to how the wind will affect you. (1 in 60, works a treat), if you know your tas, and from the h/twind your gs, you can your out your time.(miles per minute, 120kts = 2 miles per min and so on.

if its a long diversion, then after the first check point, youll know if you were right or not.


practice on the ground, after a while, you can draw a line on a map and guess the heading and distance within a maybe 5 degrees and 2 or 3 miles.......


or somthing like that.........

[FlyingForFun]

Also not an instructor, but I'll answer anyway:

If you have to divert for real, it's likely to be a high-stress time. One of the most likely reasons is bad weather. Another is a technical problem which means you'd be happier on the ground. Under these kind of circumstances, the last thing you want to be doing is worrying about a wind computer! Not to mention that it's a bad idea to have your head inside the aeroplane doing calculations at any point during the flight.

A rough estimate in your head will probably be accurate enough. But my instructor taught me a neat little trick. On my plog, I have a "wind star" - an 8-pointed star for each of the 4 points of the compass as well as the 45-degree points. Before the flight, I work out the drift (degrees left or right) for each of the 8 points. Then, for a diversion, pick the closest point and apply wind drift.

Quick and simple - it won't take your mind off the task in hand, or your eyes away from your traffic scan.

FFF
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[pondlife]

I'm not an examiner, but an instructor.
I'd be extremely surprised if any examiner cared much what method and tools you used for airbourne diversion planning so long as
1) it didn't affect your ability to fly the plane safely and keep a lookout while you were doing it and
2) it produces appropriately accurate results.

For my own students I would advise them (quite strongly) against using either a wizz wheel or an electronic wotsit to do the sums when airbourne because they both would require enough manual skill to operate that the flying of the aeroplane and keeping a lookout is likely to suffer too much. Either should produce an answer that is much much more accurate than is needed and I would always teach to use a "rule of thumb" method based on some fairly easy mental arithmetic. That way they can carry on looking out the window while they're doing the simple sums in their head.
There's loads of different rule of thumb methods, all of which would produce results which are plenty accurate enough - I suggest that you discuss this with your instructor to find one that you both agree is OK for you.

You don't need to be 100% accurate with this stuff - the wind won't be exactly what was forecast and I bet you can't fly 100% accurately in a light single anyway - I certainly can't. The important thing is to get something that's fairly accurate and then have some method for correcting any errors. Again, a track error correction method is something that you should agree with your own instructor - there's lots of them.

Hope that helps a bit.

[StrateandLevel]

tmybr

"I know that in pre-flight planning I must use a whiz wheel"

I would hope that you will learn to do your planning without a Wizz Wheel. The wizz wheel is a tool that allows you to be a little more accurate however, you can and will make mistakes with it! that means that you have to do a mental cross check.

If you are capable of checking it, you can also obtain the results by the same process, negating the wheel entirely.

If a student on a diversion produced one I think I would confiscate it; as an examiner I want to see a diversion conducted without it.

From a safety perspective, using a wizz wheel in the air, single pilot, is on a par with driving down the fast lane of the M1 sending text messages on a hand held phone!

[kala87]

Whiz wheels are great for pre-flight planning but I've never attempted to use one in the air in a light single. I might be tempted to use one if the aircraft had a reliable autopilot and I had a passenger who could scan for traffic while I had my head down.

I was taught a rather neat method to assess drift, heading, ground speed and timings which doesn't overtax the grey matter.

1. Always write down the forecast winds aloft on your flight log.

2. If a diversion is required, plot the track on your map. Having a ruler with built in rotating protractor helps. Write down the new diversion track.

3. Using the nearest forecast wind for your altitude, calculate the amount of drift. If the forecast wind is 60 degrees or more off your track, allow 6 degrees per 10 knot of wind speed. For a difference of 30 degrees, allow 3 degrees per 10 knots. A wind speed of 20 knots would double these drift figures. A wind speed of 5 knots would reduce the drift correction by half.

4. Next, calculate the headwind component. A wind of 60 degrees off the heading is equivalent to half the wind speed. A 45 degree difference is equivalent to two-thirds the wind speed. A 30 degree wind angle is equivalent to 100% of the wind speed. Reduce or increase your TAS by this amount, depending on whether you're dealing with a headwind or tailwind.

5. IAS/TAS conversions aren't worth doing unless you're 6000 ft or higher. Then add 10% to IAS per 6000 feet. Calculate elapsed times using 120 knots ground speed = 2 miles per minute, 90 knots = 1.5 miles per minute.

It sounds complicated but once you've done it a few times in the air, you get faster and it works fine.

[witchdoctor]

Also, make sure you know your 6 times table. Helps avoid mathematical cockups on timing after everything else has been worked out perfectly.

"Yes sir, my ETA at our diversion will be......(mutter to self: 52 miles at 145 kts is....14.5 miles in 6 minutes.....3x6=24.....plus 3 = 27 minutes)......out by 6 minutes" DOH!!!!! :8

[Tinstaafl]

Or grab the CR type whiz wheel in your shirt pocket & have the answer in a second or two...


I've used my whiz wheel more times than I can count. Not just for standard, accurate time/dist/fuel calcs inflight. Also for:
* Reach (position/altitude) by (time/place) ATC instructions
* Lose x minutes by (position) ATC instructions
* actual wind from drift/TAS/GS (several times over a period to gauge trend) to use for an accurate in flight range calculation after calculating max. allowable headwind/min. required tailwind before a diversion is mandatory.
*PNRs & CP/equitime points
* fuel to load at next landing to ensure a certain amount of capacity at a subsequent refuel point.
* conversion functions eg fuel amounts, pax questions about where/when/time stuff.
* finding alon- track groundspeed using an off-track DME (need a CR for this, not a slide type.

[B2N2]

I don't think using the whizwheel in the airplane is more dangerous than checking the T&P's as far as head down time.
The wind should still be in there and for the reason of diversion I teach to fly the airplane rudder only for the time it takes to figure out the heading/time.
I require max. accuracy(within reason) for the diversion calculations, if the weather is marginal VFR 5 degrees off track over 60 miles could make you miss the airport all together if you're flying over fairly featureless terrain. If the reason for diversion is mechanical you sure as hell want to be ending up over the airport not 5 miles left of it!:} :} :}