Among the common piloting mistakes discussed by top flight instructors back in April was a tendency of pilots new and old to fly too fast on approach. That error is but a part of a broader group of missteps and less than ideal techniques centered on the approach to landing.
As we have in the last few issues, Rotor & Wing sought out an experienced flight instructor to discuss the issue in more detail and share some techniques for avoiding or correcting common piloting errors. These articles are less an effort to lay out definitive rules for coping with such errors than one to stir debate on flying mistakes and how to overcome them.
For the review of approach tips and techniques, we turned to Bijan Moazami, proprietor of Bijan Air, a flight school, sales, service and maintenance center and electronic news-gathering operation based in Ann Arbor, Mich. Bijan Air operates the MD500, Bell JetRangers and Schweizer 300s and 333s. A longtime helicopter instructor pilot with tens of thousands of hours, “Bijan is a really great guy and an incredible helicopter pilot and flight instructor,” said Pete Schweizer of Schweizer Aircraft, which has signed off on Bijan Air as a sales and service center.
“Basically, in a normal type of flight, we have three types of approaches,” he began. A shallow approach is considered a glide slope of 5 deg., “generally, for almost any helicopter.” A normal approach is 10 deg. and a steep one is 15 deg. or more. The difficulty and sensitivity to errors each increases with the angle.
There are several common problems or common mistakes in approaches, he said.
“I personally think approaches are more important than takeoffs,” he went on. “If a pilot makes a mistake on the takeoff, generally he is lower to the ground and the outcome could be a hard landing. But a mistake on approach could result in fatalities.”
One common mistake is flying an approach at the wrong angle for the situation. As an example, Moazami cited a pilot who is flying into a confined area. “His instructor taught him that, for a confined area, you have to do a steep approach,” he said. “But the area is so large that he can basically fly a normal approach. My theory in helicopter flight is never make two emergencies out of one. So, consequently, if he can make a normal approach, why is he making it harder for himself by flying a steep approach?”
Another common mistake is not managing the aircraft’s sink rate.
“Sink rate in a helicopter could be a disaster,” Moazami said, “because the conditions could be such that there is not enough power at the bottom of the approach to stop the sink rate and make a normal landing.”
When the sink rate is high, it requires more power to stop the aircraft from sinking, “so the pilot puts himself in a tight, tight corner.
“Sink rate is a killer, believe me,” he said. “I’ve seen so many accidents, even with larger helicopters.”
A good way to start an approach, he said, is with no more than 500 fpm.
Halfway through the approach, reduce that to 300 fpm. “If I would see a student or an applicant start his approach with 1000, 1400, 1500 fpm, then, as an examiner, I would fail you,” he said. A normal approach does not require a descent rate of more than 1000 fpm.
“That would almost be classified as an autorotation. It is not an approach. An approach has to be completely managed. The helicopter should be completely under the control of the pilot all the way to the hover point or to the ground contact. It doesn’t matter.”
Generally, Moazami believes you can almost judge what kind of pilot a flier is by observing how he or she makes an approach.
“It is best to be very conservative in approaches because conditions change,” he explained. “For example, in mid-winter every aircraft has plenty of power. Consequently if the pilot makes a mistake on the sink rate and it is higher than desired, he has enough power to stop it.
“But if the same pilot gets used to those kind of approaches, when it becomes mid-summer and 90F with a full tank of fuel and two or three passengers on board or something close to max gross weight, he will not have the luxury of being able to stop the helicopter as he did in winter time.
“So to manage the sink rate is very, very critical in approaches.”
|Moazami recommends managing descent rate and ground speed by reducing each proportionally to put the aircraft in a stable, 3-ft hover over the planned touchdown point. “The best approach that a pilot can make with a helicopter, regardless of the type of approach, is the one that, at the very end, requires no flare whatsoever,” he said.|