Gear Warning System Plus:

A LAK-17 comes in for landing at Issoudun late in the daytime, when almost completely dark. Several cars light the runway with their headlamps. The pilot makes it, however did not lower his gear. Landed on his belly with quite some damage to the fuselage. The brand new LAK did not have a gear warning system.

A pilot in a Discus takes off at Issoudun in an air tow. When some hundred meters in the air, the airbrakes extent itself. Airbrakes were closed at take off, but probably not properly locked. The pilot is warned in time by his mates, so no serious situation evolved. The Discus did not have an active indication for unlocked airbrakes.

A pilot in an ASH-25 with a passenger in the second seat was on a long double airtow from Tenant Creek to Alice Springs. Over a very big forest, but just in reach of the airfield for the ASH-25, the tow pilot had to release the double cable because the other glider on the tow took him out of control. This other glider with 15 m span landed safely on the highway. The ASH-25 was just above the glidepath to the airfield, but still could not make it for some reason. About 5 minutes after the cable incident the ASH-25 pilot found out that the airbrakes were still slightly open as they had frequently been during the tow to keep the cable straight. The highway was to narrow to land on, except for a short piece the tow pilot had found just in time. While close to landing on that piece of road a severe accident almost occurred with a dark colored car driving a few feet below the glider in the same direction. The pilot managed to land the ASH-25 at stalling speed just behind the car which drove on if nothing had happened. A big road train stopped in time as well as some regular cars. The ASH-25 did not have a warning indication for unlocked airbrakes.

After some 30 minutes of flight one could hear a pilot calling his mate “Whiskey Whiskey , your gear is still down”. The WW did not have an indication for gear down and locked.

Found this story at rec.aviation soaring:

Last month an IS29D2 preparing for x-country took off with deployed spoilers. The tow pilot noticed it and tried to inform the pilot, however there was no radio. The glider pilot didn't close the spoilers. At the end the glider was released right over the airport. The pilot realized the higher than expected sink rate and tried to glide to the nearest thermal where other gliders were circling. At half distance he realized that he couldn't make it. Still not aware about the opened spoilers!! Turned back to the airport and because of the much reduced performance of the glider hit some buildings and finally landed on a road. Fortunately there was no traffic on this road at that time... Janos Bauer.

My comment: I guess the IS29D2 did not have a warning indication for unlocked airbrakes.

Just five examples of occurrences noticed or experienced by myself with either the airbrakes, the gear or a combination of those. Many pilots with some years of flying experience can make such a list, no doubt.

Made some thoughts about it and came up with a rather simple but very effective system. Designed a warning system consisting of two microswitches, three very bright LEDs and a small loud beeper to be placed in the instrument panel (IP), wired together in a sensible way.

I installed the system succesfully in our new Ventus-2cxT.

Works great on the basis of:

* 2 LEDs on (left and right) when landing: (airbrakes unlocked, gear down and locked, fig. 1)

* 1 LED on (right) at take off: (airbrakes in and locked, gear down and locked, fig. 2)

* 0 LEDs on in normal flight: (airbrakes in and locked, gear up, fig. 3)

* flashing LED and beeper to alarm: (gear up when landing, fig. 4)

* flashing LED and beeper to alarm: (airbrakes unlocked at take off, fig. 5)

The diagrams for the five possible combinations of airbrakes and gear are shown below in five modes of the system. In fig. 5 a pressure switch is closed (no pressure while on the ground); in the other figures the pressure switch is open (pressure during flight).

If you have any questions or comments on the system do not hesitate to contact me at kpt9(at)planet.nl

Hope nobody without the above system will experience difficulties; regretfully since 1974 when I started gliding I noticed several incidents and even accidents.

ir. K.P. Termaat

Arnhem, 16/sep/20003