Pilots should always be aware of the glider’s normal  attitudes for all flight regimes. Then, when presented with  an instrument failure or erroneous indication, the pilot has  a general sense of the glider’s normal attitude from outside  flying cues to make a safe return and landing. Judging the  altitude or airspeed of the glider without the guidance of  instruments should not constitute a panic in the cockpit as  many pilots can make precision approaches and landings  without the use of an altimeter. In fact, many older and vintage  gliders do not require an operational altimeter in the cockpit.  If the airspeed indicator appears to be erratic or inaccurate, fly  the glider by pitch attitude. Keep the nose of the glider at the  proper pitch attitude for best glide or minimum sink airspeed.  Additional cues to airspeed include control “feel” and wind  noise. At very low airspeeds, control feel is very mushy and  wind noise is generally low. At higher airspeeds, control feel  is crisper and wind noise takes on a more insistent hissing  quality. The sound of the relative wind can be amplified and  made more useful in airspeed control by opening the sliding  window installed in the canopy and by opening the air vent  control. During the landing approach, maintain adequate  airspeed using cues other than the airspeed indicator. Fly  the approach with an adequate margin above stall airspeed.  If conditions are turbulent or the wind is gusty, additional  airspeed is necessary to penetrate the convection and to  ensure adequate control authority. If in doubt, it is better to be flying 10 knots faster than optimum airspeed than it is to be  10 knots slower. Altimeter failure may result from internal instrument failure  or from external causes, such as water ingress in the static  lines. Regardless of the cause, it is important to maintain  sufficient altitude to allow a safe glide to a suitable landing  area. During the approach to land without a functioning  altimeter, it is necessary to rely on perception of maintaining  a safe gliding angle to the target landing area. The primary  risk to safety is entering the approach from an altitude  that is lower than normal. It is better to enter the approach  from a normal height, or even from a higher-than-normal  height. During the approach, judge the angle to the target  area frequently. If the angle is too steep, apply spoilers/ dive brakes to steepen the descent path. If necessary, apply  a forward slip or turning slip to lose additional altitude. If  the approach angle is beginning to appear shallow, close the  spoilers/dive brakes and, if necessary, modify the approach  path to shorten the distance necessary to glide to make it to  the target landing area. Static line contamination affects both the altimeter and the  airspeed indicator. If it is suspected that either instrument  If the canopy opens while on aerotow, it is vital to maintain  a normal flying attitude to avoid jeopardizing the safety of  Canopy-related emergencies are often the result of pilot  error. The most likely cause is failure to lock the canopy in  the closed position prior to takeoff. Regardless of the cause,  if the canopy opens unexpectedly during any phase of flight,  the first duty is to fly the glider. It is important to maintain  adequate airspeed while selecting a suitable landing area. Compass failure is rare, but it does occur. If the compass  performs poorly or not at all, cross-check current position  with aeronautical charts and with electronic methods of  navigation, such as GPS, if available. The position of the  sun, combined with knowledge of the time of day, can help  with orientation also. Being familiar with section lines and  major roads often provides helpful cues to orientation and  the direction of flight. Variometer failure can make it difficult for the pilot to  locate and exploit sources of lift. If an airport is nearby,  a precautionary landing should be made so the source of  the problem can be uncovered and repaired. If no airport is  nearby, search for clues to sources of lift. Some clues may be  external, such as a rising smoke column, a cumulus cloud, a  dust devil, or a soaring bird. Other sources are internal, such  as the altimeter. Use the altimeter to gauge rate of climb or  descent in the absence of a functioning variometer. Tapping  the altimeter with the forefinger often overcomes internal  friction in the altimeter, allowing the hand to move upward  or downward. The direction of the movement gives an idea of  the rate of climb or descent over the last few seconds. When  lift is encountered, stay with it and climb. It is essential that a glider pilot be familiar with the procedures  for making a safe approach without a functioning airspeed  indicator or altimeter. Being accompanied by a glider flight  instructor during the flight review provides an excellent  opportunity to review these procedures. is malfunctioning because of static line contamination,  remember that the indications of the other instrument(s)  connected to the static line may also be incorrect. Use the  external cues described above to provide multiple cross- checks on the indications of all affected instruments. If in  doubt about the accuracy of any instrument, it is best to believe  the external cues and disregard the instrument indications.  After landing and prior to the next flight, have an aviation  maintenance professional evaluate the instrument system. Airspeed Indicator Malfunctions Altimeter Malfunctions Compass Malfunctions Variometer Malfunctions Glider Canopy Malfunctions Glider Canopy Opens Unexpectedly  8-21