When go-around is impossible-defining the point of no return
Total preparedness and full briefing can avoid risky last-second decisions.
Calculated go-around (aborted landing roll) groundspeed and maximum safe elapsed time before go-around is initiated with a 1000-ft "indecision" distance, hydroplaning surface and maximum thrust reversers deployed (0.20 g or 3.80 kts/s). Go-around speeds and elapsed times as a function of touchdown/lift-off speeds and actual touchdown (air) distance from the threshold are shown for a 5500-ft runway.
Low deceleration has a detrimental effect on minimum go-around speed. To calculate a minimum safe go-around speed (decelerate to and accelerate from), one needs to subtract the touchdown (air-distance) and configuration-change/inertia-distance from the LDA.
The upper table on p 112 summarizes the minimum safe go-around speed and safe deceleration elapsed time for a runway length of 5500 ft. The nose gear touchdown point was variable-1500, 2500 and 3500 ft.
We assumed that the main gear would touch down first, followed by nose gear derotation in the next 3 sec, defining the total air-distance. Inertia-distance and/or configuration-change-distance can vary dramatically. We assumed 1000 ft for "normal" pilot reaction (about 5 sec).
The fast 500-ft configuration-change-distance does not make much of a difference. The liftoff groundspeeds (GS) are 120, 130, or 140 kts. Density altitude, tailwind and excessive landing speed are thus indirectly included.
The pilot may use somewhat slower liftoff speed-the minimum-unstick airspeed Vmu-but this certification airspeed is normally not published or available to pilots. The lower table on this page shows the rejected landing-roll minimum safe go-around speed and the elapsed time to slow to it, based on a hydroplaning aircraft without thrust reversers.
Calculated go-around (aborted landing roll) groundspeed and maximum safe elapsed time before go-around is initiated with a 1000-ft "indecision" distance, hydroplaning surface and no thrust reversers deployed (0.05 g or 0.96 kts/s). Go-around speeds and elapsed times as a function of touchdown/lift-off speeds and actual touchdown (air) distance from the runway threshold are shown for a 5500-ft runway.
To illustrate this methodology using an example, let us assume a pilot touches down 2500 ft from the threshold of a 5500-ft runway at a GS of 130 kts. Deploying thrust reversers (see upper table) and using whatever friction braking might be available on the hydroplaning surface, the pilot has only about 6 sec (slow down to about 106 kts) to determine whether a go-around is appropriate and take first action.
If the pilot continues slowing down, he might stop in the next 3200 ft or so, provided there is no hydroplaning below 100 kts and assuming maximum thrust reversers until full stop. The aircraft will have exited the runway, but at a low speed.
Obviously, the runway contamination and the pilot performance plays crucial role. It is that initial deceleration that can completely confuse the pilot. If the airplane is not equipped with thrust reversers (see lower table), trying to stop would theoretically consume an additional 7800 ft.
Since the runway remaining is only 3000 ft, the airplane would overrun the runway at high speed, causing certain damage and injuries. A decision to go around is prudent, but the pilot has only about 8 sec from nose-gear touchdown to make that decision and start taking action.
Interestingly, thrust reversers are a mixed blessing. While obviously helping to slow down faster, they bring a pilot to a worse situation by giving him/her less time to decide if a go-around is appropriate.
We can conclude that, if the thrust reversers are used, a decision to go around should be abandoned unless initiated in the first few seconds after touchdown. But can such a short time give pilots enough clues to what to expect on the runway? It is not easy to make a radical change in mindset and go from the "stop-stop" to the "go-go" decision.
Beechjet 400A pilots perform a night approach to IAD (Dulles, Washington DC). Landing on a contaminated runway at night may be particularly hazardous since judging deceleration visually is far more difficult in darkness. It is important to touch down on the fixed-distance markers at the correct airspeed.
Not only do the inertia of the aircraft and delay time in configuration changes play significant roles-so does the inertia in the human decision-making process. The pilot must make up his/her mind before touchdown and know when the point of no return on the runway is reached.
A touchdown should not be attempted at all if there is any suspicion of serious runway contamination and poor braking. Clearly, being at the proper airspeed and touching down on a fixed-distance marker gives the corporate pilot more options.
Pilots continue to discuss and debate all aspects of the go-around, whether in large venues such as safety meetings or between each other in the cockpit. Since most readers will have been in a conversation at one time or another regarding the go-around decision, they would likely agree that nearly everyone says they'd have no problem making the right decision if and when faced with it.
So why do pilots still make the wrong choice more often than they should? Unfortunately, it seems most pilots almost hate to go around. The missed approach procedure is always discussed during the approach briefing, but never the circumstances that would precipitate a go-around. It becomes almost a formality.
Pilots fail to execute a go-around for all kinds of reasons. There's that smooth landing everyone tries to make, regardless of how far past the landing zone they float. They may be behind schedule, or the weather may be stormy, or they're overconfident in the performance of their aircraft-or pride may make them hesitate to make that go-around.
Failing to establish realistic go-around "markers"-or not exercising the discipline to follow them-can leave a pilot with the choice those pilots in this article probably found themselves having to make-and it's an impossible choice.
At that point the only questions remaining are whether it's better to accept a landing overrun, perhaps with serious consequences, or try an "impossible" go-around that will end catastrophically.
Luck versus judgment
Although an "airborne" go-around is often discussed in initial pilot training, and in just about every new aircraft training program thereafter, it is not analyzed thoroughly enough or trained well enough into new pilots-or, even more so, into some seasoned pilots.
We suggest that the decision on rejected landing-roll and go-around takeoff be made during the approach briefing. In this way, no time is wasted on the runway should a touchdown occur and further action be required.
This situation is potentially more dangerous than the V1-cut, and surprisingly little attention has been given to it. From initial training on, pilots are taught to make decisions based on known performance parameters.
The decision-making process in this case breaks down completely, and the indecision and hesitation that result just compound the problem-as does the fact that you, as a pilot, may not recognize that your airplane is not performing as well as you expect.
Even after receiving all available information regarding braking action, and the data in the aircraft operating manual, things may not go as planned. This in turn can lead to what FAA's Pilot Handbook of Aeronautical Knowledge calls a "poor judgment chain," in which one bad decision often leads to another.
As this string of bad calls grows, it limits the number of follow-on alternatives for continued safe flight. This in turn often erodes any situational awareness and the ability to execute sound risk management.
Hopefully, this article will prompt pilots to revisit their go-around parameters before touchdown and rethink some of those situations where they thought, "Man, we should have gone around back there-we were lucky."
Nihad Daidzic is associate professor of aviation
of the Aviation Dept at Minnesota State University, Mankato MN.
Thomas Peterson is an ex-USAF pilot serving as
assistant professor of aviation in the same department.
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