Mike Barrett, McAlpine Helicopter's chief pilot, sees the UK Civil Aviation Authority attitude to helicopter operations as enlightened, compared with the restrictive regulations in other European countries.
After an initial period of reservation, the CAA has been practical and co-operative in establishing criteria for the newspaper operation. McAlpine is confident that city rooftop pads have significant advantages over ground-level pads for safety, environmental, and utility reasons. The elevated platform allows improved clearance of surrounding obstructions, particularly in the event of engine failure during approach or departure. It ensures low noise disturbance (amazingly, this operation has received almost no noise complaints from local residents in more than three years).
Rooftop platforms may come in handy for rapid fire and medical evacuation. Few buildings in London's crowded skyline are stressed to take the weight of helicopter. Many roofs are cluttered with air-conditioning vents, railings, and other impedimenta which would make even an emergency landing a hazardous undertaking.
Perhaps designers of city tower blocks should give thought to the beneficial role that the helicopter can play as a public service vehicle. This is one of the fastest growing areas of helicopter usage in the USA today.
CAA regulations stipulate that the diameter of an elevated pad should be at least 2 times that of the helicopter's rotor—some 88ft in the case of the Twin Squirrel. In addition, the pilot must be able to lift-off from the pad to a Critical Decision Point (CDP) 90ft above the pad elevation, lose one engine, and either land safely clear of the building or continue with a single-engined departure without sinking to less than 35ft above pad elevation.
The square International Press Centre roof measures 46ft x 46ft, and the Twin Squirrel, with its 35ft rotor diameter, can meet neither requirement with a normal lift-off technique.
McAlpine Helicopters has developed special procedures to meet the CAA criteria. These have been demonstrated to, and approved by, the CAA, and involve a lift-off to 15ft above the pad, followed by a climb in backward flight, keeping the pad in sight through the pilot's lower right-hand windshield. This reverse climb is continued to the 90ft CDP.
Single-engine safety is vital
In the event of an engine failure below this point, the pilot uses the departure pad as his emergency landing area. Should failure occur after CDP, a transition into descending forward flight is made, maintaining the minimum 35ft margin above roof elevation while accelerating to the take-off safety speed (Vtoss) of 40kt. Under IFR conditions the pilot must fly level, accelerating further to his best singleengined climb speed of 55kt (Vy), before starting his en-route climb. Under VFR, 40kt will be maintained in the climb until 550ft above departure elevation, before acceleration to 55kt.
Similar criteria apply for approach and landing, with a Landing Decision Point (LDP) 90ft above pad elevation. Engine failure above LDP entails a missed approach procedure, similar to the departure profile. Below LDP power loss entails landing on to the roof.
Before landing on the IPC, pilots take an engine condition reading to ensure full engine performance before starting an approach, wind 8mb off the London QNH (equal to the 240ft height of the helipad building), and then make an approach into wind (using local chimney smoke, or the flags on the Houses of Parliament two miles away) to land on the nearest into wind diagonal line across the roof.
This ensures the maximum landing dispersion distance, which allows leeway for the pilot's fore/aft touchdown error.
To the passenger the landing appears dramatic and, indeed, there is little room for error. Despite this,
McAlpine research and development pilot Geoffrey Holder makes the technique look easy.
He has played a major part in developing the rooftop techniques to the standards required by the CAA. Up to three passengers can be carried from the roof, together with the plates. In fact, there needs to be at least one passenger, in the copilot's seat, to prevent an aft e.g. position allowing the tail boom to strike the edge of the building.