Tow Failure Without Runway To Land Below Returning Altitude
If an inadvertent release, towline break, or a signal to release from the towplane occurs at a point at which the glider has insufficient runway directly ahead and has insufficient altitude (200 feet above ground level AGL) to make a safe turn, the best course of action is to land the glider ahead. [Figure 8-12, panel 2] When flying at higher elevations, a higher altitude return may be necessary to return to the runway due to increased ground speed and air density. After touchdown, use the wheel brake to slow and stop as conditions permit. Attempting to turn at low altitude prior to landing is very risky because of the likelihood of dragging a wingtip on the ground or stalling the glider. Landing ahead and slowing the glider as much as possible prior to touching down and rolling onto unknown terrain is usually the safest course of action. Low speed means low impact forces, which reduce both the likelihood of injury and risk of significant damage to the glider. Gliders pilots should always be looking on both sides and ahead trying to plan for the best area to land in the event of a premature landing. The greater amount of altitude the glider pilot has the greater number of options that are open to them during an emergency. Landing under control is always preferable to the “perfect” landing area almost within glide distance.
Tow Failure Above Return to Runway Altitude
A downwind landing on the departure runway may be attempted if an inadvertent release, towline break, or signal to release from the towplane occurs after the towplane and glider are airborne, and the glider possesses sufficient altitude to make a course reversal, which is determined by wind crab angle, wind velocity, and glider groundspeed. [Figure 8-12, panel 3]
The course reversal and downwind landing option should be used only if the glider is within gliding distance of the airport or landing area. In ideal conditions, a minimum altitude of 200 feet above ground level (AGL) is required to complete this maneuver safely. Such factors as a hot day, weak towplane, strong wind, or other traffic may require a greater altitude to make a return to the airport a viable option.
The responsibility of the glider pilot is to avoid the towplane, if the tow is terminated due to a towplane emergency; the tow pilot is also dealing with an emergency situation and may maneuver the aircraft abruptly. The glider pilot should never follow the towplane down if the towplane is experiencing engine problems or engine failure.
After releasing from the towplane at low altitude, if the glider pilot chooses to make a turn of approximately 180° and a downwind landing, the first responsibility is to maintain flying speed. The pilot must immediately lower the nose to achieve the proper pitch attitude necessary to maintain the appropriate approach airspeed. If a rope break occurred in the process, the glider pilot should release the rope portion still attached to the glider to avoid any entanglement on landing with the glider.
Make the initial turn into the wind. Use a 45° to 60° bank angle as necessary to make the course reversal to the departure. This provides a safe margin above stall speed and allows a course reversal turn to be completed in a timely manner. Using a bank angle that is too shallow may not allow enough time for the glider to align with the landing area. An excessively steep bank angle may result in an accelerated stall or wingtip ground contact. If the turn is made into the wind, only minor course corrections should be necessary to align the glider with the intended landing area if the glider was allowed to drift downwind. Throughout the maneuver, the pilot must maintain the appropriate approach speed and proper coordination. Remember to keep the yaw string straight and ball centered (see Turns section for more information on the yaw string).
Downwind landings result in higher groundspeed due to the effect of tailwind. The glider pilot must maintain the appropriate approach airspeed. During the straight-in portion of the approach, spoilers/dive brakes should be used as necessary to control the descent path. Landing downwind results in a shallower than normal approach. Groundspeed is higher during a downwind landing and is especially noticeable during the flare. After touchdown, spoilers/dive brakes and wheel brakes should be used as necessary to slow and stop the glider as quickly as possible. During the later part of the rollout, the glider feels unresponsive to the controls despite the fact that it is rolling along the runway at a higher than normal groundspeed. It is important to stop the glider before any loss of directional control.
Tow Failure Above 800′ AGL
When the emergency occurs at or above 800 feet above the ground, the glider pilot may have more time to assess the situation. Depending on the gliderport/airport environment, the pilot may choose to land on a cross runway, into the wind on the departure runway, or on a taxiway. [Figure 8-12, panel 4] In some situations, an off-gliderport/ off-airport landing may be safer than attempting to land on the gliderport/airport.
Tow Failure Above Traffic Pattern Altitude
If an emergency occurs above the traffic pattern altitude, the glider pilot should maneuver away from the towplane, release the towline if still attached, and turn toward the gliderport/ airport. The glider pilot should evaluate the situation to determine if there is sufficient altitude to search for lift or if it is necessary to return to the gliderport/airport for a landing. Pilots should remember their obligation when dropping objects from an aircraft according to Title 14 of the Code of Federal Regulations part 91, section 91.15, and not create a hazard to persons and property on the ground. [Figure 8-12, panel 4]
Slack line is a reduction of tension in the towline. If the slack is severe enough, it might entangle the glider or cause damage to the glider or towplane. The following situations may result in a slack line:
- Abrupt power reduction by the towplane
- Aerotow descents
- Glider turns inside the towplane turn radius [Figure 8-13]
- Updrafts and downdrafts
- Abrupt recovery from a wake box corner position [Figure 8-14]
When the towplane precedes the glider into an updraft, the glider pilot first perceives that the towplane is climbing much faster and higher than it actually is. Then, as the glider enters the updraft, it is lighter and more efficient than the towplane. It climbs higher and faster than the towplane did in the same updraft. As a result, the glider pilot pitches the glider over to regain the proper tow altitude but gains airspeed more quickly than the towplane, hence the slack towline. The glider pilot must be ready to control the descent and closure rate to the towplane by increasing drag.
Slack line recovery procedures should be initiated as soon as the glider pilot becomes aware of the situation. The glider pilot should try slipping back into alignment with the towplane. In the event that slipping motion fails to reduce the slack sufficiently, careful use of spoilers/dive brakes can decelerate the glider and take up the slack. As the towline begins to tighten, stabilize the tow and gradually resume the desired aerotow position. When slack in the towline is excessive, or beyond the pilot’s capability to safely recover, the glider pilot should immediately release from the aerotow.
Common errors regarding a slack line include:
- Failure to take corrective action at the first indication of a slack line.
- Use of improper procedure to correct slack line causing excessive stress on the towline, towplane, and the glider.
- Failure to decrease drag as towline slack decreases.