a Boeing 737-700 recently completed successful technical demonstration
test flights that proved its performance capabilities and
in high-elevation, high-terrain environments.
Paro International Airport,
in the kingdom of Bhutan,
is high in the Himalayan Mountains. At 7,300 ft (2.23 km) above
sea level, with a runway 6,500 ft (1.99 km) long, surrounded by
deep valleys and 18,000-ft (5.48-km) peaks, Paro is one of the worlds
most difficult airports for takeoffs and landings.
In February 2003, a Boeing
737-700 successfully completed 11 test flights at Paro International
Airport. The series included two technical demonstration flights
and eight customer relations flights with Druk Air Royal Bhutan
Airlines, the national airline of Bhutan. Druk Air, which operates
two 72-passenger BAe 146-100 jets from Paro to six cities in five
countries, is considering upgrading its fleet and extending its
routes. The rigorous test flights proved that the 737-700 is capable
of meeting all performance and procedural requirements for safe
operations at Paro and other airports in high-elevation, high-terrain
The 737-700 performed
flight maneuvers as predicted and met or exceeded performance expectations
for simulated one-engine-inoperative maneuvers, which were accomplished
by reducing thrust on one engine to idle power. The expected performance
levels proved conservative when compared with the demonstrated performance
of the 737-700.
Test flight data were
verified by flight data recorder (FDR) information, indicating that
predicted airplane performance is representative of actual airplane
performance as recorded by the FDR.
The test flights verified
procedures for takeoff and landing operations at Paro. The 737-700
demonstrated engine-out takeoff procedures, which is required for
Paro operations, engine-out missed approach and go-around procedures,
and Druk Air procedures for landing on both directions of the runway
This article discusses
demonstration test flight airplane.
demonstration test flights description.
demonstration test flight analysis.
TECHNICAL DEMONSTRATION TEST FLIGHT AIRPLANE
The demonstration airplane
was a 737-700 Boeing Business Jet (BBJ) configured with blended
winglets and a business jet interior (fig.
1 and table
1). The 737-700 BBJ used for the demonstration flights is aerodynamically
equivalent to the commercial variant of the 737-700 being offered
to Druk Air.
TECHNICAL DEMONSTRATION TEST FLIGHTS DESCRIPTION
On February 6, 2003,
two technical demonstration test flights were accomplished from
runways 33 and 15 at Paro International Airport. Boeing pilots Captain
Buzz Nelson and Captain Van Chaney flew the 737-700 accompanied
by the Druk Air chief pilot on the first flight and a senior first
officer on the second flight.
To prove the capability
of the 737-700 at Paro, the technical demonstration flights had
to show that the airplane could take off following a simulated single
engine failure at the most critical point during the takeoff ground
roll (V1) and safely return to the airport on one engine.
Terrain in the valleys
surrounding Paro limits takeoff performance. Flight operations into
and out of Paro only occur when the visibility in the valley is
clear. This visibility is required to allow an airplane to turn
around safely within the steep valley walls and reach the minimum
safe altitude to depart the valley or return to the airport in the
event of an engine failure.