Insights

I'm shocked whenever I encounter a multiengine pilot or instructor who uses the airplane's blue-line airspeed for the final approach speed - a frequent occurrence, I'm sorry to say. The airspeed indicator's blue reference line denotes a performance speed, pure and simple. It represents vyse, the single-engine best rate-of-climb speed or, if the airplane won't climb or maintain altitude with one engine shut down, the minimum rate-of-descent speed.

The correct final approach speed, published in the airplane's pilot's operating handbook (POH), is slower than the blue-line speed. You adjust the POH speed for airplane gross weight variations and wind gusts, and you use this adjusted speed for both one- and two-engine approaches.

The weight-variation rule of thumb decreases the POH approach speed by one percent for every two-percent increment of gross-weight reduction. For example, an airplane's maximum gross weight is 4,000 pounds, its actual gross weight is 3,600 pounds, and the POH final approach speed is 90 knots. This airplane is 10 percent below gross weight, so you should reduce the POH airspeed five percent or five knots, approximately.

For wind gusts, I add half of the gust value. If the wind is gusting to 15 knots, I increase the weight-corrected POH speed seven or eight knots.

advocates of blue-line speed justify using it by referring to airspeed variations between airplanes, runway length, and single-engine missed approach considerations. Different airplanes have different final approach speeds, and some pilots who routinely fly more than one multiengine airplane feel that blue-line approaches are acceptable because blue-line airspeed is a safe, easily identified speed that eliminates memorizing the POH approach speed for each airplane.

Others say the blue-line speed is acceptable because they always land on long runways, but many of these pilots are moving up the aviation ladder. When they transition to jets, using a limited-length runway becomes a common occurrence, and the pilot who has not learned to use the proper approach speed is in for a rude awakening. So, too, is the multiengine pilot who normally operates from long runways, but is forced to make an unanticipated, emergency single-engine landing on a short runway.

Float, float, and crash might summarize what happens then.

The single-engine go-around is the final and most intense argument used by blue-line pilots. They say, "Maintaining blue-line airspeed protects the single engine go-around capability."

Hogwash.

The go-around is performed at VY, the two-engine best rate-of-climb speed, a speed that's at or above blue-line speed. When you use the proper technique during a go-around, the airplane will accelerate quickly to VY.

You can prove this fact at a safe altitude by flying a simulated, single-engine approach at the POH speed with gear and flaps extended. Perform a go-around, but while you set takeoff power and retract the last increment of flaps, maintain the existing pitch attitude. Now glance at your airspeed. It has increased to blue-line speed or faster, and now you should increase pitch attitude, confirm a positive rate of climb - I hope - and retract the landing gear.

Instructors must teach correct procedures, and students must establish proper habits early in their flying career so examiners and evaluators will not question their competency - a true setback for anyone who aspires to be a professional aviator. Regardless of what you fly, always pretend that every runway is short, always use the correct final approach speed, and always land on the numbers. Practice makes perfect.