This article is about things to do (and not do) on a cross-country glider flight when you are well below your planned height band, have already selected a field or airport to land in, and are trying to stave off that landing. Within this subject, we must talk about thermaling low, which is a very dangerous practice – especially in windy and gusty conditions. It is also a controversial subject that some writers address by a blanket rule of “don’t thermal below “X” altitude.” While that may be reasonable, I believe the decision on when to abandon thermaling and execute the landing is an individual one that should be determined by the pilot after a careful inventory of many factors including experience, currency (both general and in particular glider), wind and gust conditions, time of day, quality of the field or runway, approach obstructions, personal comfort, degree of tiredness, and (especially for pylon type motor gliders) whether there will be an attempt to start an engine before the land out -requiring more altitude in reserve. While I state no rule about this, it must always be remembered that a land out is just an inconvenience, and something quickly forgotten. But a crash is a disaster that at best reverberates throughout an entire flying career – and at worst ends that career entirely. If there is any question of safety, the decision must be made in favor of terminating the flight.
“Hope is not a strategy” –
a note affixed to the instrument panel of Dick Butler’s Concordia
If you fly gliders cross country, you will get to this place sooner or later: The flight has not gone according to plan, we are now low and approaching a land out (either at an airport or in a field) and have only a few hundred feet of altitude (before committing to land) to work with and save the flight. We have already selected our field or runway and decided the approach that we will use to get into it. We are no longer progressing on the course ahead. But there is still some time and spare altitude to work with. So, mindful of Dick Butler’s pithy observation stated above, how can we use that limited time and altitude to maximize the possibility of a “save”? Here are some ideas that have worked for me over the years and that you may find helpful.
Prepare for the fight.
It’s only natural to postpone physiological tasks like eating, drinking, and urine elimination until you are high, cool, and relaxed. But that can be a mistake if you have a long tough climb-out battle ahead of you, especially at a hot low altitude. Once you get below say, 2000’ AGL, do a quick inventory of these things and deal with them promptly before you get really low. We must stay hydrated and keep electrolyte levels up to fly well. And the constant pressure of needing to urinate can make the ground seem much more attractive than grinding out a 0.5 kt thermal.
Get the glider as far upwind of the landing target as possible
Leave enough altitude for a zig-zag flight path back to the target. This technique allows us to locate and work very weak lifts and still drift with the wind toward the safe landing spot. If we search downwind of the landing spot for lift, a weak thermal will take us away from where we need to be and if the climb is unsuccessful, we can easily consume all of our altitude trying to get back upwind to a rushed landing. If your landing target is an airport runway then try to avoid the traffic pattern in your search area if you can, but still, get the glider upwind as the first order of business.
Do not cover the same ground twice
Your search upwind of the target field should be a triangle, a zig-zag, or a sideways “W” that takes you over likely thermal sources (infrastructure, tall buildings, farm silos, rail yards, towers, feedlots, junkyards, large power lines, and metal structures) that will trip or focus thermals. Avoid cool or wet areas like swamps, ponds, fields with puddles, or irrigated crops. You can collapse or expand the triangle or zig-zag flight path depending on changes in your altitude reserve. The problem with heading straight out from the selected landing field toward a single likely thermal source is that if it doesn’t work, you must cover the same useless terrain on the return trip. This wastes time and altitude. Frequently when I review a land-out flight trace for a beginner, I see something like a bow tie or shoelace knot pattern clustered around the ultimate landing spot. That thrashing around back and forth to the same point is a waste of time and altitude. Your final flight trace should not backtrack over itself. Source: ‚Whingsandwheels, Roy Bourgeois‘.