Marco conceptual

3.1. General

Ground movement starts from the parking stand to the take-off run, and from the end of the landing roll to the parking stand.

Many crew members are not aware that taxiing is one of the most critical phases in low visibility conditions. Aerodrome complexity and traffic density contributes to increase the risk of:

– Mistake in location and identification of taxi routes to be followed,

– Collision with vehicles or other aircraft on the maneuver area, at taxiway intersections or along taxiways, – Unauthorised entry to an active runway.

The most hazardous situation comes from an unauthorized entry on to an operational runway. In restricted visibility or at night this can happen without the ATC controller being immediately aware of the situation. On airports approved to support Low Visibility Operations, active runways are clearly and unmistakably marked. The most common cause of unauthorised runway incursion is a misunderstood clearance. The crew believes that it has been cleared to enter or cross a runway and proceeds unless there is some obvious, immediate, danger.

Language difficulties, busy environment, confusing phraseology, congested radio frequencies, cockpit distractions, time pressure, and similarity of call signs are all factors which may result in a misinterpretation of what has been said. Conversely, a good understanding of the over-all situation (gained by monitoring the ground frequency), a systematic request of clearance confirmation at the slightest doubt, a confirmation of clearance to enter a runway by visual signals (e.g. stop bars if installed) are good means to reduce the risks associated to a misunderstood clearance.

3.2. Recommended procedures

The following procedures could give support in conducting safe and efficient taxi operations

3.2.1. Prior to taxiing

Q_{Prepare and read low visibility taxi charts (when published),}



Q_{Determine the expected taxi route to be followed,}



Q_{Perform a briefing with a detailed description of the routing between the apron and the holding point by using}

the airport chart and/or the low visibility taxi charts (when published); ensure that both crewmembers under- stand the expected taxi route,



Q_{Identify the main intersections, the direction changes, the holding positions and the areas to be avoided,}



Q_{Write down the taxi clearance when received (CM2 copies it on the Nav Log or through the scratch pad which}

can be easily use as a short notepad),



Q_{Amend the taxi briefing in accordance with the taxi clearance before commencing taxi,}



Q_{Adjust the pilot’s seat and rudder pedals so that it is possible to apply maximum braking with full pedals deflec-}

tion,



Q_{Start engine 1 before taxiing,}



Q_{On ATR -600 select the airport moving map on both MFD,}



Q_{On ATR equipped with an Electronic Flight Bag, activate the airport moving map.}

3.2.2. During taxi

Q_{In low visibility conditions taxi with more caution, and at slower speeds,}



Q_{Both crew members must be concentrated on the visual surveillance and on the identification of taxi routes to}

be followed. Consequently:

– Both CM1 and CM2 must have their taxi charts visible,

– The flight crew should postpone all unnecessary activity and duties,

E - Flight crew operating procedures

E.

Flight crew operating procedures

– Taxi actions and checklist, before take-off briefing and company communication are performed preferably when the aircraft is stopped,

– CM2 should follow taxi progress on the airport diagram, check consistency of taxiway orientation with aircraft heading, call out all signs to verify position.

– On ATR -600 CM1 and CM2 control aircraft position on the airport moving map (please refer to Paragraph E.4,

Low Visibility Take-Off).



Q_{Always use taxi light to visually indicate movement. (When entering any active runway ensure all exterior lights}

are illuminated).



Q_{Read back all clearances: If any crewmember is in doubt regarding the clearance, stop the airplane and verify}

taxi routing against the written clearance or with ATC.



Q_{In case of malfunction or if a problem occurs during taxi, stop the aircraft, set parking brake, and inform ATC}

before performing any action.



Q_{If and when the crew feels lost or has any doubt on their position, they must ask ATC for help.}

3.2.3. Prior to approach phase

Q_{When low visibility conditions exist at destination, the approach briefing should include a detailed description of}

the routing from the runway exit to the apron area. Potential difficulties should be addressed in reference to the airport chart and/or low visibility taxi charts (when published).



Q_{As crew members establish contact with the company staff at destination, they request the assigned stand}

number to confirm (or eventually amend) the briefing.



Q_{If it is necessary to cross a parallel runway after landing, the standard procedure is to hold short between run-}

ways. The crew members must monitor the tower frequency and be sure to have received a clearance to cross the runway before proceeding.

3.3. Usual difficulties

Changes in visibility or light intensity, the disappearance of familiar landmarks, the use of a rarely employed taxiway or runway, an excessive concentration on the taxiway centreline can all contribute to mistakes in location identification and positioning.

Figure E1: Low Visibility taxiing

Pilots can get confused at intersections if they do not see the signs indicating which taxiway they are crossing. The problem lies in the fact that the signs are placed a fair distance before the intersection - an important feature which allows the crew to anticipate -, and that they are not repeated as a confirmation of the intersection. In fact, at a given intersection, the only visible signs may be those for the next intersection.

For a variety of reasons pilots may face a change of route during the taxi phase: taxiing to the gate is most difficult when the route is changed in mid-stream. Once pilots get a mental picture of the route they need to take from the runway to the gate, it is hard to replace it with another route. Such situation requires increased vigilance during taxi routing and whilst in visual surveillance

E - Flight crew operating procedures

3.4. Airport moving map

3.4.1. Electronic Flight Bag (EFB)

The PilotView® _{EFB can be fitted on any ATR version. EFB Chart viewer applications are provided by Jepessen, Lido}

or EAG. These interactive viewers allow the display of the aircraft position on the airport charts, from the aircraft GPS position input. During taxi, this is particularly interesting for pilots maneuvering around unfamiliar airports. This efficiently increases situational awareness and reduces runway incursions.

3.4.2. ATR -600

The airport NAV provides the flight crew with aircraft progression on airport surface by displaying an aircraft symbol on the airport map. Nevertheless the other aircraft are not displayed on the map.

Such device is of real assistance to the pilots: it increases efficiency and safety during low-visibility surface operations.

Figure E2: Airport moving map