Arrival Height

The term arrival height comes from the construction of a final glide in cross country flying. Returning home the pilot builds a faster/steeper or a slower/flatter glide depending on the strength of soaring conditions. The pilot must then add a safe arrival height to the calculation to allow for unknown sink along the way and to have enough altitude to fly a good landing pattern. Interestingly, the seemingly showy contest finishes we cross country pilots love to do are nothing more than converting that cautious arrival height into cross country speed once the field is made and then back into height for landing.

Arrival height in our local flying is just as important for safety. Arrival height is the key to consistently safe patterns and landings at Harris Hill.

Be back home over the pattern side of the Harris Hill plateau at 1000 ft AGL on all local flights.

Arrival height is not the same as the height the pilot begins the downwind leg. That is the IP (Initial Point) altitude. 800 ft AGL is the altitude to be at starting downwind leg. That leaves 200 feet of margin in case sink is encountered returning to the pattern and to maneuver onto the downwind leg. There are a couple ways to be sure to get back to the pattern area at 1000 ft AGL. A pilot can make calculations using a conservative glide ratio for the glider. For example, the ASK-21 gets 34:1 on its best day. Using 30:1 which is 200 ft/nm is safe way to operate. Most local flyers don’t bother with all that and simply move closer to the pattern area as the glider gets lower. Using either method, in trying to achieve proper arrive height on every flight most pilots will return and be in excess of 1000 ft.

We want people to get back safely like this. For that reason, it is normal for pilots to thermal in the pattern area above the 800 ft AGL IP altitude. This is different than many gliding operations where thermalling “in the pattern” is against the rules. We want people to practice climbing away from 1000 feet because it is an essential skill for cross country flight. We don’t want people to practice this skill over the monastery, out of safe glide range of a normal traffic pattern.

Flying low on the ridge is another way pilots fail to achieve proper arrival height. At Harris Hill you may also see a pilot thermalling off the ridge below 800’ AGL, maybe even in the traffic pattern. Everyone needs to know that low level ridge flying is a special sign off in our club. A pilot needs to have skills to do a tighter pattern, a downwind landing, or a valley landing if the wind dies.

Arrival height can be used as an early indicator. As the pilot tries to return for a normal pattern it may become clear that the desired 1000 ft AGL arrival height is not happening. A pilot may be 1400 ft AGL when this realization occurs. He or she should then start to modify their planning to open up valley landing options. If returning from the east or southeast and getting low, wiggling the course northward allows the possibility of landing at the Elmira airport. From there, and with a little lift, a smart course of action may be to head back to Harris Hill via the ridge, planning a pattern on the east side of the field with the aux field as a backup. With a little more lift a normal glider pattern west of the field with a crosswind entry may once again become safely available.

A safe arrival height over a landable area is the most important consideration in operating a glider in cross country or local flight. It makes all the other principles possible.