A conventional take-off and landing flight profile was shown to cover a "noise footprint" of 20 square miles (50 km²) in line with an airport's runway when using a limit of 90 decibels, by using an approach path of six degrees (double the normal angle) and a climb out path of 15 degrees the footprint could be reduced to 3 square miles (8 km²).
This form of STOL operation was expected to be in place at British city airports by the late 1970s.
To reduce the noise footprint further to a circle with a diameter of just 3,000 ft VTOL operations were expected to commence in the early 1980s.

The suggested minimum noise take-off technique for the HS.141 was to use full power from the lift engines in a vertical climb to 250 ft (76 m) then reducing power to 83% to continue this climb to 1,000 ft (300 m).
At this height the aircraft would transition into forward flight using vectored thrust from the lift engines and then accelerate and climb to 2,000 ft (600 m) using increasing thrust from the cruise engines.
By this stage the aircraft would have reached an airspeed of 168 knots (310 km/h) and would be fully supported by its wings alone, the lift engines being shut down and covered by hinged doors.

For an approach to a vertical landing the procedure was to be virtually reversed with the approach commencing at 2,000 ft (600 m) and 4 miles (6.4 km) from the landing point.
A conventional take-off and landing flight profile was shown to cover a "noise footprint" of 20 square miles (50 km²) in line with an airport's runway when using a limit of 90 decibels, by using an approach path of six degrees (double the normal angle) and a climb out path of 15 degrees the footprint could be reduced to 3 square miles (8 km²). This form of STOL operation was expected to be in place at British city airports by the late 1970s. To reduce the noise footprint further to a circle with a diameter of just 3,000 ft VTOL operations were expected to commence in the early 1980s.
The suggested minimum noise take-off technique for the HS.141 was to use full power from the lift engines in a vertical climb to 250 ft (76 m) then reducing power to 83% to continue this climb to 1,000 ft (300 m). At this height the aircraft would transition into forward flight using vectored thrust from the lift engines and then accelerate and climb to 2,000 ft (600 m) using increasing thrust from the cruise engines. By this stage the aircraft would have reached an airspeed of 168 knots (310 km/h) and would be fully supported by its wings alone, the lift engines being shut down and covered by hinged doors.
For an approach to a vertical landing the procedure was to be virtually reversed with the approach commencing at 2,000 ft (600 m) and 4 miles (6.4 km) from the landing point.
Hawker Siddeley HS.141