Head Up Guidance at easyJet
Chief Pilot easyJet
established itself as a successful and growing low cost airline with its
innovative approach to operating aircraft in an efficient and cost effective
way. This extends to all aspects of its operations: from the boardroom to the
cockpit. The benefits for its customers are a safe, efficient and friendly
airline with very low fares. easyJet works
hard to maintain this competitive edge everywhere it can. The introduction of
Head Up Guidance Systems in the cockpit - the first UK airline to do so - is
another example of its determination to maintain this competitive edge.
easyJet has opted for the Flight Dynamics
Head-up Guidance System for its existing B737-300 fleet. easyJet objectives are increased safety, improved
operations and performance gains, which easyJet will pass directly on to its customers.
Improving safety is of great concern in an industry
that depends upon customer confidence. easyJet's purpose in adopting the Head Up Guidance
System provided by Flight Dynamics is specifically to enhance safety, to
improve its operating performance and to further improve its commercial
efficiency. Head up Guidance Systems have significant potential for improving
and enhancing the flight capabilities of aircraft. Even more benefits can be
obtained by improving the pilot's situation awareness. Consequently, achieving
these benefits is a major goal for easyJet.
2. easyJet Operating
The traditional picture of low-cost operators is of
small airlines operating mixed fleets of old aircraft at the end of their lives
on marginal routes that larger airlines are not interested in. Low cost
operators also tend to give the impression of operating on a shoestring near
the accepted limits of safety.
busts this model. It operates modern aircraft intensively on busy routes. It
operates at a profit and is expanding, buying a fleet of brand new aircraft
that will radically increase both its route structure and the intensity of its
operations. easyJet makes money by looking
at all aspects of its operations and reducing overheads where-ever and
when-ever they occur. It has an interesting cost per seat model that allows it
to compare its costs with its competitors, in order to offer the lowest
possible price to its customers. Above all, easyJet is innovative. For example, its
services are way ahead of its competitors and have firmly established
it as a favourite with its customers.
This philosophy is carried forward in all its
operations. For all passengers everywhere, safety is the number one priority.
Any airline that does not ensure the highest levels of safety is courting
disaster. Not just in terms of loss of lives and aircraft but also in the
straightforward loss of it commercial operating position. Safety is therefore,
an essential element of commercial success. Period.
|Figure 1: easyJet
operates a very modern fleet
easyJet is not
content simply to operate aircraft to the currently accepted safety standards,
but wishes to further enhance safety wherever the opportunity exists. This
means taking advantage of new navigation, surveillance and communications
technology and new procedures where these aid safety in day-to-day operations,
for example, enhanced GPWS and enhanced wind shear. There are many areas where
Head Up Guidance systems can help contribute towards this. A very
straightforward safety benefit is achieved by improving Pilot Situation
Awareness. In fact, the safety benefits of Head Up Guidance Systems have been
widely demonstrated in military aircraft - often in very difficult operating
conditions for over three decades. It is unfortunate that awareness of these
benefits has not been as visible as they could have been to civil airline
The introduction of Head Up Guidance into commercial
civil aircraft operations is long overdue. Head up Guidance allows the
introduction of flight concepts such as 'Angle of Attack', which are very
familiar to military pilots but virtually unknown to most civil pilots. Yet
these concepts will allow aircraft to be flown in a simpler and far safer
manner, permitting the pilot to fly the aircraft safely within its flight
envelope irrespective of weight, load and distribution.
3. easyJet Operating
easyJet operates a
fleet of 18 Boeing 737-300's. It has ordered a further 30 Boeing 737 -8700s
which it is currently taking delivery of. It also has options to purchase a
further 30 Boeing 737 -700/800s. The decision whether to exercise this further
option is expected to be made during 2001. There are numerous benefits to
operating a new fleet of a single type, which significantly reduce operating
overheads. These benefits include low maintenance, reduced spares holding,
reduced crew training costs and greater day-today operational flexibility. The
list of benefits is long and completely confounds traditional views of low cost
operators. Larger airlines with mixed fleets of varying ages of aircraft do not
gain these benefits.
4. Head Up Guidance Systems and Safety
The safety benefits of Head Up Guidance Systems are
well established. According to the Flight Safety Foundation: "
transport aircraft equipped with properly functioning head-up guidance system
technology, that provides critical aircraft flight guidance and performance
information to a correctly trained flight crew, will result in significantly
fewer aircraft accidents
" (Flight Safety Foundation Report). In a 1990
study of civil jet transport accident data from the period 1959 -1989, the
Foundation concluded that HGST would have prevented or positively influenced
the outcome of 31% of the accidents.
5. Rockwell Collins Flight Dynamics Head-up Guidance
The Head-up Guidance System (HGS) offers the pilot all
critical flight information head-up and superimposed on the real world.
Information is focused at infinity so no refocusing from real world to cockpit
instruments is required. This makes HGS information easy to assimilate and
natural to the pilot.
|Figure 2: Head Up Guidance System in Cockpit
The key elements of Flight Dynamics Head up Guidance
System (HGS) are:
5.1 HGS Combiner
Optically combines flight symbology with the pilot's
view through the windscreen. The holographic Combiner is designed to reflect
the light projected from the CRT in the OHU. The holographic Combiner in
effect, acts as a wavelength selective mirror reflecting the CRT color while
allowing all other colors to pass through the glass.
5.2 HGS® Computer
The HGS Computer receives input signals from aircraft
sensors and equipment and converts this data to symbology. The HGS®
Computer also evaluates both system and approach performance through extensive
Built-ln-Test (BIT), input validation and Approach Monitor processing. The
output of the HGS® Computer then goes to the Drive Electronics Unit. The
HGS® Computer is installed in the aircraft avionics bay
5.3 Drive Electronics Unit (DEU)
The Drive electronics Unit receives signals from the
HGS® computer and conditions these signals to drive the Cathode Ray Tube
(CRT) in the Overhead Unit. The DEU contains power supplies and electronic
circuitry for signal amplification, distortion and geometry corrections, and
5.4 HGS® Control Panel (HCP)
HGS® Control Panel (HCP) provides the pilot with
the ability to enter data required by the HGS® but not available from other
equipment on the aircraft.
|Figure 3: Head Up Guidance System Components
5.5 OverHead Unit (OHU)
The Overhead Unit projects the image onto the
Combiner. The Overhead Unit is mounted above the pilots head, hence the name.
The OHU also contains electronic circuitry for display, intensity control, and
5.6 HGS® Annunciator Panel
HGS Annunciator Panel provides HGS® status and
warning annunciations to the First Officer during CAT IIIa approach and landing
6. Flight Dynamics HGS Flight Modes
The Flight Dynamics HGS has 4 Modes of operation:
a) Primary Mode
This mode is similar in
format to head-down PFD/ND or EFIS Display and uses the aircraft Flight
Director to drive the guidance cue.
b) AIII Approach Mode
mode provides a decluttered display and uses unique HGS Guidance-to-Touchdown
for CAT IIIa approach and landing..
c) IMC Approach Mode This mode
also uses a decluttered approach display with Flight Director guidance for CAT
1 or CAT II approach without command flare guidance.
d) VMC Approach
This mode is typically reserved for Non-precision approaches. No
guidance cue is provided, just a straightforward Flight path only
7. The Benefits of Head Up Guidance Systems
The benefits of Head up Guidance Systems can be
quantified in three main areas:
7.1 Safety Benefits
The HGS is a powerful tool for accident prevention.
During HGS operations, the pilot is head-up looking for terrain and traffic
while monitoring all essential flight data. This 'head up, look out' rather
than 'head down, look in' paradigm, means the pilot's attention is directly
focused on the most important task - flying the aircraft, whilst being able to
monitor all critical flight data. Pilot situation awareness is greatly
improved, with the integration of all essential flight data 'head up'. This is
particularly helpful at night.
The unambiguous symbolic presentation of flight path
is a tremendous assistance in difficult conditions such as "black holes",
circling, VMC and non-precision approaches. The improvements provided by the
HGS, for Non-Precision approaches is a particular benefit. Emergency situations
such as wind-shear and TCAS can also be more easily handled, with the pilot
flying escape guidance while observing external visual references. Specific
benefits for the pilot include:
a) Conformal display of Critical Flight Parameters
- Inertial Flight Path
- Flight Path Acceleration (Potential
- Stall Margin
b) Constant view of
Flight Path and Energy State
c) Precise Aircraft Control
e) Improved Manual Touchdown Precision
g) Tail-strike Avoidance
h) Recovery from unusual
6.2 Operational Benefits
Day-to-day operational benefits include the following:
6.2.1 Improved CAT I minima
Lower Cat I Minima can be achieved for aircraft
equipped with HGS, irrespective of the nature of the facilities at the airport.
In all cases, HGS gives direct and quantifiable operating benefits:
|Type of Facility
||RVR without HGS
||RVR with HGS
Table 1: Improvements in RVR achievable with
6.2.2 Cat II operations on Cat I runways
Head Up Guidance enables Cat II operations to take
place on CAT I runways, providing the following improvements are also carried
out at the airport:
This necessarily implies that approval to operate in
these conditions must be given on an airport-by-airport basis.
6.2.3 Improved Cat III Operations
HGS is certified for Manual Cat IIIa Approach and
Landing Capability with a decision height of 50ft. and 200M RVR. It is also
certified for low-visibility take-off, allowing operations down to 75M RVR.
This means those early morning flights on foggy days will get off on time,
allowing the company to maintains its schedule throughout the day. There is
also the potential for Cat IIIb operations via the 'Hybrid' or 'Super Fail
Passive' method. In this approach, the pilot utilizes the fail-passive Cat IIIa
autoland and the HGS to monitor the performance of the autoland for approaches
down to 150M RVR.
|Figure 4: Head Up Guidance in CAT III at 50
The above enhancements to aircraft operating
performance means that the HGS system offers direct and improved airline
on-time performance by avoiding the flight disruptions normally associated with
poor visibility conditions as well as the 'knock on' effects of such
disruptions. Improvements in take off reliability are particularly good. These
benefits can be directly quantified by straightforward examination of
historical local meteorological conditions and simple calculation of the
'before and after' of installing HGS. These improvements mean smoother and more
reliable flight operations, which in turn, mean less disruptions affecting
aircraft scheduling, crew rostering etc.
6.3 Commercial Benefits
The improvement in landing and take off reliability
also translate into direct and indirect commercial benefits. Passengers have a
far greater assurance of arriving at their destination despite conditions that
hamper most carriers. These improvements in reliability mean improved customer
perceptions of the airline and confidence in its operations, which means that
customers come back more often. Operating costs are also reduced (crew time,
fuel, tyre and brake wear etc.). It is reasonable to expect reductions in
diversions and go-rounds and overall reductions in general wear and tear on the
|Figure 5: Economic Model for HGS
Commercial and economic benefits can be calculated in
terms of avoiding revenue loss, additional revenue gains (increase in
passenger/cargo loads) and gains made in operating costs.
7. Certifications and OEM Relationships
The Flight Dynamics HGS has a wide range of
certifications and is offered by the following manufacturers:
Flight Dynamics' HGS has more in-service experience
than any other commercial HUD System - at over 6 millions flight hours. It has
over 3 million flight hours in-Service experience on Boeing 737s. In all, over
25,000 Low-Visibility Operations have been carried out. To date, over 1000
systems have been delivered.
8. The future
easyJet will work
with both the UK Civil Aviation Authority and local airports to maximize the
benefits of Head Up Guidance in its daily operations. This will mean breaking
new ground in the UK, as easyJet is the
first UK airline to commit to Head Up Guidance systems. Flight Deck operating
procedures have to be formalised with the UK CAA. Pilot qualification and crew
training for Head Up Guidance requires simulator training and appropriate
facilities and training programmes will be established to meet easyJet's needs as its aircraft fleet grows steadily
over the next few years. easyJet will
continue to seek further improvements in safety, operations and commercial
returns as each of these can be passed directly on as benefits to the customer.
This means exploring the full potential of Flight Dynamics HGS in all its
The key benefits of Head Up Guidance Systems are
straightforward. When integrated on an aircraft, an HGS increases the
aircraft's operational capability and significantly improves the Pilot's
Situational Awareness. It also improves manual Flight Path Control and provides
a platform for further growth for new technologies. HGS offers a clearly
quantifiable financial return on investment. easyJet will seek further improvements in its low
visibility operations, in taxi guidance, and for take off and landings.