Safety Spotlight: Stabilized approach economics

The first incident involved a pilot recently checked out in a Diamond DA40. He flew a few hours to Southern California, but was tired when he arrived. On final, he knew he was high and fast, but felt he could still make the landing work. After landing long, he applied the brakes hard and stopped before the end of the runway.

I was the next person to fly the airplane. Before climbing into the rental aircraft with a client, I rolled it forward to inspect the main tires for flat spots. In the process, we discovered both tires had the largest flat spots I’d seen in my long flying career. That pilot paid $800 for new tires and labor to change them.

The second pilot didn’t fare as well. After not flying for a month, he flew his Cessna 182 to a nearby airport to practice landings. After a few good landings at Half Moon Bay Airport, he returned to the airport in Palo Alto, California. Approaching the field, he relaxed because he was returning to his “home field,” with which he was very familiar. Ironically, relaxing was the wrong thing to do. Palo Alto’s runway is among the shortest many pilots will encounter.

Like the first pilot, he was high and fast. He considered going around, but felt he could save the landing. He landed long and hard, and bounced. The aircraft then contacted the runway in a nose-low attitude, and the nose gear collapsed as it skidded to a stop. The cost to replace a near-TBO engine, propeller, a wing tip, and the bottom of the engine compartment will exceed $100,000. Like the first incident, this one could have been avoided by a timely go-around.

On November 10, 2015, a chartered Hawker departed Dayton, Ohio, for Akron, about 30 minutes away. While many factors contributed to this fatal accident, two stood out. The clouds at Akron were 600 feet overcast, and the pilots apparently spent time discussing whether clouds are measured from the ground or sea level. With more than 9,000 hours in flying time between the two pilots, I was surprised they didn’t know unquestionably that clouds are measured from the ground. If you ever forget, just think about a METAR for 1,000-foot clouds over Denver. Could they possibly be 4,000 feet below the ground? Obviously not, which confirms that cloud heights are reported in agl, not msl.

Another major factor was that the Hawker was not on a stabilized approach. One of the pilots apparently said to the other, “You’re diving. You’re diving. Don’t dive—2,000 feet per minute, buddy! Two thousand feet per minute! Don’t go 2,000 feet per minute!” Soon after, the aircraft broke out of the clouds, but the pilots didn’t arrest their high descent rate and crashed into the ground, killing all on board.

So what is a stabilized approach, and why does it matter? Cirrus Aircraft’s flight operations manual gives a good description: “A stabilized approach is characterized by a constant angle and constant rate of descent approach profile ending near the touchdown point. Stabilized approach criteria apply to all approaches including practice power-off approaches.”

It goes on to say that for VFR landings, an approach is considered stabilized when all of the following criteria are achieved by 500 feet agl:

• Proper airspeed,

• Correct flight path,

• Correct aircraft configuration for phase of flight,

• Appropriate power setting for aircraft configuration,

• Normal angle and rate of descent,

• Only minor corrections are required to correct deviations. “A go-around must be executed if the above conditions are not met, and the aircraft is not stabilized by 500 feet agl,” it said.

Undoubtedly, all the pilots in these incidents knew they should have gone around, or executed a missed approach. But none did. For all of them, it was a costly lesson on the economics of unstable approaches.