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Windshear Recoveries in the B-777
Harry Walker
United Airlines
30 Jun 1998
I. Overview
This test was conducted as an evaluation of the effects of two different engine models on the
performance of the B-777 during windshear recoveries. Of interest was the performance in
respect to altitude loss with the PW 4000 engine (74000 lbs thrust) and the PW 4084 engine
(90000 lbs thrust).
II. Equipment Description
The evaluation was conducted on the B-777 simulator number one at UAL DENTK. It
contained all aero models for the B-777 as well as being fleet representative of the current
UAL fleet.
III. Data Acquisition
F/O Harry Walker and Mr. Bill Dobbs (DENTK Sims) conducted the evaluation. The
simulator was placed at a representative gross weight (approx. 445,000 lbs.) and altitude
(2000 Ft). All events were flown using the autocoupled approach to a autopilot recovery.
Test conditions were standard day, Gear down, Flaps 30, V Ref 141 KIAS, ILS RWN 26
DEN, windshear model number 7. Four event sets were flown. Set One with the PW 4000
engine, recovery at 800 ft RA (radio altitude). Set Two was the same as set one with recovery
at the point where airspeed spiked to +15 knots and then returned to V Ref. Set Three was
with the PW 4084 engine with recovery at 800 ft RA. Set Four was the same as set three with
recovery as in set two. Data at attachment one was automatically generated by the simulator
windshear recovery-training program.
IV. Findings / Results
On average the PW 4000 engine configuration had a 233 ft altitude loss with a min airspeed of
97 KIAS during the recovery. The PW 4084 engine had a 185 ft loss with a minimum airspeed
of 100 KIAS.
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V. Conclusions / Recommendations
The data at attachment one shows the positive effect of extra thrust during windshear
recoveries. If increased thrust is available to the pilot it should be used to increase the safety
margin. As windshear is a random event a direct correlation between events is not possible
but in the aggregate extra thrust increases the aircraftÕs ability to avoid ground contact in the
event of windshear.
Attachment One
Windshear Recovery Events
B-777 Data Sheets
On File
Revision 14.0 37
Appendix B
Flight Test Results Of The Controlled Flight Into Terrain Avoidance
Maneuver In Fly-By-Wire Transports
I. Abstract
Controlled Flight into Terrain (CFIT) is the leading causes of aviation accidents.18
A test program was developed to compare the CFIT maneuver performance capabilities of
aircraft with hard versus soft Fly-By-Wire (FBW) flight control systems. To obtain this data,
simulated CFIT avoidance maneuvers utilizing a Boeing 777-300 and an Airbus A330-200
were performed. These tests were performed at the Boeing Flight Test Facility in Seattle,
Washington and the Airbus Flight Test Facility at Toulouse, France.
This flight test had a two-fold purpose. The first was to evaluate the effectiveness and
appropriateness of a recovery technique that was developed for convention aircraft without
regard for the flight envelope protections incorporated in modern FBW aircraft. The second
purpose was to develop and/or evaluate CFIT escape maneuvers that utilize the maximum
capability of the aircraft afforded by the protections incorporated in their respective FBW
flight control systems.
As a direct result of this flight-test activity, one major US operator of Airbus aircraft (United
Airlines) has changed the CFIT escape maneuver for these aircraft.
II. Introduction
A. Purpose of Flight Test
· To evaluate the effectiveness and appropriateness of a recovery technique that was
developed for convention aircraft without regard for the flight envelope protections
incorporated in modern FBW aircraft.
· To evaluate and/or develop CFIT escape maneuvers that utilize the maximum capability of
the aircraft afforded by the protections incorporated in their respective FBW flight control
systems.
18 CFIT Training Aid, section 3 page 3.3.
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B. Ground Proximity Warning Systems
Transport aircraft are equipped with a variety of Ground Proximity Warning Systems
(GPWS). These systems will usually, depending upon sophistication, warn the flight crew 5
to 60 seconds before impact. The most advanced system is the Enhanced GPWS that uses a
terrain data base and compares current aircraft position to known terrain hazards, contained in
an onboard database. This system can provide a full 60 seconds of warning before terrain
impact.
C. CFIT Escape Maneuvers
A CFIT escape maneuver is usually performed in response to a GPWS warning and is a
　
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