Aviation

GPS has really revolutionised flying. As well as the expensive panel avionics that are fitted to new aircraft (and being retrofitted to older aircraft), cheap hand-held GPS units are adding to the old navigation techniques that have been a traditional part of flying. Here are some of the great things about using GPS in the cockpit as a VFR or visual pilot:

• It tells you your groundspeed – no more calculating by timing from landmarks and playing with the E6B sliderule.
• It helps your situational awareness by allowing you to cross-check where you think you are on paper maps against where you actually are – they're supposed to match.
• The GPS helps keep you on-course because you can quickly detect and comensate for any changes in the wind that may have occured since the flight was planned.
• Position reports become very accurate and can simply be read off the screen.
• ETAs can just be read off the screen rather than stringing a series of calculations together (they're usually more accurate too).
• It frees up time in a very busy environment so you can concentrate on keeping the plane in the sky, and enjoy the view!

There are two directions you can go as a VFR pilot. You can buy a specialised hand-held designed for flying, or you can buy a bog-standard GPS receiver.

Portable aviation GPS units have some features built into them that can make for a safer flight. Aviation GPS units have proper aviation maps, combine this with the fact they know where you are, and they can warn you if you are about to bust airspace. They have a continuous display that can tell you where the nearest airport is and they can help with fuel calulations. It is possible to plan an entire flights on these units. A good example is the Garmin GPSMap 96.

However, there are some good reasons why you do not need to own an aviation specialised GPS. For a start, the aviation units are very expensive compared to a standard receiver. You pay for the additional testing, features and the expensive Jeppeson aviation map that is loaded onto the unit. Secondly, aviation maps go out of date and you have to keep buying expensive updated maps from Jeppeson. Paper maps are much cheaper!

Standard units can tell you groundspeed in knots, your ETA in UTC time and your distances in nautical miles. If you load all the airports along your route into your unit, then a quick "Find Nearest" can show you the nearest airport. If you are buying a new GPS specially for flying, then a mapping GPS should be your first move. Even the ugly Garmin base-map can allow you to check your position against the paper map and identify that small town 2 miles off the left wing.

Of course it goes without saying that a GPS unit should never replace proper pre-flight planning. I still do all my sums and take them along just in case. If the GPS unit were to fail for any reason, then you should still be able to get yourself home by using all those hard-won and practiced tecniques that have served generations of pre-GPS pilots.

Karl Summerfield (fnk)