The Landing Criteria Spectrum
The landing criteria spectrum is a topic I enjoy discussing with developing aviators (at the end of the day, that includes all of us). Many disciplined pilots, especially newer ones, prefer highly prescriptive guidance. However, the reality is that you can only prescribe so much. There are simply too many variables to make linear, one-size-fits-all decisions that can be easily executed in the air.
As a result, pilots must be ready to exercise a degree of judgment and flexibility. The more work you do preparing on the ground, the better your airmanship will be in the helicopter. Landing criteria for helicopter malfunctions is one of those deceptively complex concepts that new aviators might overlook.
Understanding “Land as Soon as Possible”
The definition is straightforward: Execute a landing at the first site where a safe landing can be made.
However, as aviators and rescuers, we are constantly weighing the risk of an operation against the potential gains of success. We strive to mitigate risk while optimizing mission success, ensuring that the risk is justified.
Consider an urban environment: a vacant little league field might seem like a safe landing site—provided the emergency procedure (EP) calls for it. But factor in obstacles like fences, light posts, and wires, or environmental variations like night conditions, and that same landing site may no longer meet the criteria for “safe.”
Take, for example, an H-60 malfunction where both the #1 hydraulic pump and backup hydraulic pump fail (#1 HYD PUMP caution without the BACKUP PUMP ON advisory). This condition requires a “land as soon as possible” response, but for a safe landing, it also demands a long, flat, ideally paved surface—preferably a runway.
If no additional aircraft damage is present and there is no correlation between the failure of the transmission driven pump (#1 hydraulic pump) and electrically driven pump (back up pump) that would indicate failure of the #2 hydraulic pump is imminent, while serious, this situation leans closer to the “land as soon as practicable” side of the spectrum potentially warranting some extended flight to a site where you can better assure a safe landing.
The Other End of the Spectrum
By contrast, main transmission malfunctions fall on the opposite side of the landing criteria spectrum—almost reaching land immediately. These failures are progressive and can render the helicopter un-flyable.
While pilots should avoid exacerbating a bad situation by rushing a landing and risking collision with obstacles like power lines or fences, with a land a soon as possible transmission malfunction, transitioning to a high hover (the next best option after being on deck or in a low hover) above obstacles, followed by a vertical landing, might be the safest choice.
Examining the Spectrum
Where do other “land as soon as possible” EPs fit within this framework? What environmental or situational factors shape your assessment of a “safe landing site”?
Likewise, consider “land as soon as practicable” EPs. If mission success outweighs the risk, some failures fall toward the least urgent end of the spectrum—such as a GEN BRG caution when the APU is running and conditions allow for daytime VMC.
On the other hand, HYD RSVR LOW EPs lean toward the “land as soon as possible” side of the spectrum.
Even within the same EP, symptoms may place a failure at different locations on the spectrum. For example, a decreasing MXMSN PRESS entering the yellow range is far more concerning to me than a MXMSN OIL PRESS caution with stable indications on EICAS.
Final Thoughts
Considering the nuances within the landing criteria spectrum can shape better decision-making under duress. As you review emergency procedures, consider experiencing the malfunctions under various circumstances and how those circumstances effect where you are on the landing criterium spectrum. How does the risk, or remaining in the air, compare to the risk of landing at a certain location?
