9.3 Loss of Separation

Exercise 1.1.1 Read and translate the text.

The incident is described below took place in the middle of the day in the terminal area near a major European airport. The three aircraft involved were operated by major European airlines. The details of the incident have been changed to protect confidentially but the facts are very much as they happened.

Factual Information

AirB123 is a Boeing 737 which is intending to land at the airport and is descending to FL 100 under control of the Initial Approach Controller (INI). At 12.00, INI instructs the pilot of AirB123 to “proceed VOR, for radar to ILS RW 25R”.

Two minutes later at 12.02, the pilot of CAir035, an Airbus A340 departing from the airport, informs Departure Control (DEP) that he is climbing to FL90 and proceeding to LMN. DEP instructs him to continue towards LMN and report reaching.

CAir3365 is an Airbus A320 at FL90 on the same route as CAir035 but 10 miles ahead, also under control of DEP.

At 1205.00, Cair035 advises levelling at FL90 and request further climb. Unfortunately, the callsign is corrupt and DEP believes the message came from CAir 3365. He issues the instruction: “CAir 3365 climb report level FL200”.

DEP does not notice that the wrong aircraft has responded to the clearance.

A few seconds later, INI detects the conflict and instructs AirB123 to turn left heading 300. He advises AirB123 the he has “traffic 11 o’clock 5 miles same level, climbing”. He then instructs AirB 123 to “descend immediately to FL70”.

At 1205.50, DEP issues the instruction: “Cair035 maintain FL90, traffic crossing right to left, tern left heading 120”.

But Cair035 had already passed FL90. Five seconds later he reports “We have a TCAS TA. Traffic is in sight”.

DEP responds:”Cair035 descend immediately FL90, turn immediately left heading 090”.

At the same time, CAir035 receives a TCAS “climb” RA. He replies: ”Descending FL90, left 150 degrees, following TCAS”.

In fact the pilot continued to descend, contrary to his “climb” RA.

At 1206.30, AirB123 informs INI that he has the traffic in sight on his right hand side. The aircraft pass 1.5nm apart, both at FL90, descending.

Analysis

Two aircraft with callsigns Cair035 and Cair3365 departed from the same airfield on similar initial tracks within a few minutes of each other. The potential for callsign confusion (same prefix, two digits in each suffix the same) was apparently not detected by the airline callsign deconfliction programme nor was it noticed by the controllers or the pilots of either aircraft.

The request from Cair035 for further climb was corrupt and the call sign was unclear. The DEP controller was expecting a climb request from Cair3365 and so assumed the call was from that aircraft and issued it with a clearance to climb to FL200 without first checking the call sign.

The pilots of Cair035 were expecting further climb clearance and accepted the clearance as being intended for them.

The DEP controller did not detect the error on readback. The fact that the pilot of Cair035 abbreviated his callsign at 1205.16 may have contributed to this error.

The pilot of Cair035 received a TCAS “climb” RA and reported to ATC that he was following it however he apparently continued to descend in accordance with ATC avoiding instructions.

LOSS OF SEPARATION – From several safety occurrences we recommend:

Communication and Similar Callsigns

• Use correct RTF phraseology, procedures and discipline at all times;

• Insist on readback. Listen carefully to readback. Always correct errors and insist on correct readback following an error for as many times as it is necessary to ensure that the correct clearance has been understood;

• Monitor flight crew compliance with RTF callsign use;

• Take extra care when language difficulties may exist;

• Recognize and understand the pilots’ working environments and constraints;

• Warn the pilots of aircraft on the same RTF frequency having similar callsigns that callsign confusion may occur. If necessary, instruct one or both aircraft to use alternative callsigns while they are on the frequency;

• A transmission could be blocked when two or more aircraft are responding to the same clearance. Typically the controller would hear a partial or garbled readback.

• If a blocked transmission is suspected, ensure that both aircraft retransmit their messages and confirm that a clearance has not been taken by an aircraft for which is was intended;

• Where an actual or potential callsign confusion incident is observed, file a report using the national mandatory incident reporting system or voluntary incident reporting system as appropriate;

• Advise adjacent sectors/airports if it is felt that potential confusion may exist between aircraft likely to enter their airspace;

• Ensure that aircraft operators are made aware of any actual or potential callsign confusion reported by air traffic controllers.

TCAS

• Where a collision risk exists, ACAS provides the most effective means of collision avoidance.

• When a controller is informed that a pilot is following an RA, he should not attempt to modify the aircraft flight path until the pilot reports returning to the clearance. He should provide traffic information as appropriate.

The EUROCONTROL Level Bust Toolkit contains further information to reduce the potential for loss of separation.

Exercise 9.3.2 Answer the questions.

1. What does Initial Approach Controller instruct the pilot of the Air B123?

2. What does DEP instruct?

3. What does DEP believe?

4. What instruction does the controller issue?

5. What doesn’t DEP notice?

6. What happened a few seconds later?

7. What did the pilot report five seconds later?

8. What was corrupt and unclear?

9. What didn’t the DEP controller detect?

10. What fact may have contributed to the error?

11. What did the pilot of CAir035 receive?

12. What did the pilot of CAir035 report to ATC?

13. What were the recommendations according to this incident?

Exercise 9.3.3 Write T if the sentence is true and F if the sentence is false.

1. A Boeing 737 is climbing to FL 100.

2. Some minutes later the pilot of CAir035, an Airbus A340 departing from the airport, informs that he is climbing to FL90.

3. The DEP controller detected the error on readback.

4. The pilot of CAir035 received a TCAS descent.

5. The pilot continued to climb in accordance with ATC restrictions.

6. Listen immediately to readback.

7. Monitor flight crew compliance with RTF callsign use.

8. A controller should try to modify the aircraft flight path.

9. If necessary, instruct one or both aircraft to use alternative callsigns.

10. An information could be blocked when two or more aircraft are asking for the same clearance.

11. Normally the controller would hear a partial or garbled readback.

Exercise 9.3.5 Give the English equivalents for the following.

Приземлиться в аэропорту; две минуты спустя; доложить занятие; неверный вызов; на том же маршруте; борт в поле зрения; повернуть немедленно; ошибка; слушать внимательно; исправлять ошибки; предупреждать пилотов об опасности; советовать; смежный сектор; сокращенный позывной

Exercise 9.3.6 Find in the text synonyms for the following words and word combinations.

Mistake/fault; primary; course; false/mistaken; later; nevertheless; solicitude; compulsory; mistake; limitation; change; plane; alike; opposite; spoilt; say again; contemplate; tenseness.

Exercise 9.3.7 State what part of speech the following words belong to.

1. Initial

a) adjective b) adverb c) noun d) preposition

2. route

a) adverb b) noun c) preposition d) adjective

3. wrong

a) noun b) adverb c) preposition d) adjective

4. further

a) adverb b) adjective c) preposition d) noun

5. apparently

a) preposition b) adjective c) adverb d) noun

6. however

a) adverb b) noun c) preposition d) adjective

7. under

a) adjective b) adverb c) preposition d) noun

8. procedure

a) preposition b) noun c) adjective d) adverb

9. care

a) noun b) adjective c) adverb d) preposition

10. typically

a) adjective b) preposition c) noun d) adverb

11. mandatory

a) noun b) adverb c) preposition d) adjective

12. loss

a) noun b) adjective c) preposition d) adverb

Exercise 9.3.8 Match the words and word combinations in column A with those in column B.

A	B
1. further climb	a. предотвращение столкновения
2. incorrect callsign	b. подобные/похожие позывные
3. descend immediately	c. риск столкновения
4. at the same time	d. если необходимо
5. within a few minutes of each other	e. обеспечивать информацией о воздушном движении
6. in accordance with	f. подать доклад
7. avoiding instructions	g. оба самолета
8. use correct procedures	h. трудности языка
9. language difficulties	i. использовать правильные процедуры
10. both aircraft	j. в соответствии с …
11. to file a report	k. в пределах нескольких минут друг от друга
12. similar callsigns	l. в то же самое время
13. if necessary	m. снижаться немедленно
14. a collision risk	n. неправильный позывной
15. to provide traffic information	o. дальнейший набор
16. collision avoidance	p. указания для избежания столкновения

Exercise 9.3.9 Fill in the gaps with the words from the text choosing from the ones given in brackets.

1. Boeing 737 is ______ to land at the airport. (trying, intending, operating)

2. An airbus is on the same _______ (level, route, airway)

3. He advises Air B123 that he has “______ 5 miles same level” (traffic at 11 o’clock; traffic; other traffic)

4. The pilot informs that he has the traffic in sight on his ______ hand side (left, right).

5. The pilot _____ (got, received, sent) a TCAS “climb” RA.

6. ______ (Control, Monitor, Advise) flight crew compliance with RTF callsign use.

7. Take extra care when language ____ (importance, difficulties, necessity) may exist.

8. Instruct one or both aircraft to use ____ callsign (alternative, the same, another)

9. ACAS provides the most ______ (necessary, effective) means of collision avoidance.

10. In fact the pilot _______ to descend, contrary to his “climb” RA (began, continued, followed).

Exercise 9.3.10 Fill in the gaps with the related words.

1. Two minutes ____ (late) the pilot informs that he is climbing to FL 90.

2. CAir 035 advises _____ (level) at FL 90.

3. ____ (Fortunate), the callsign is corrupt.

4. Another traffic is ____ (cross) right to left.

5. The callsign was ___ (clear).

6. He continued to descend in accordance with ATC ____ (avoid) instructions.

7. Listen ____ (careful) to readback.

8. Recognize and understand the pilots’ ____ (work) environments.

9. _____ (Typical) the controller would hear a partial readback.

10. Ensure that both aircraft _____ (transmit) their messages.

Exercise 9.3.11 Fill in the prepositions if necessary.

1. A Boeing 737 is intending to land _____ the airport.

2. At 1202 an Airbus A340 departed __ the airport.

3. CAir 3365 is an Airbus A320 _____ FL 90 _____ the same route.

4. The Initial Approach Controller instructs AirB123 _____ turn left.

5. Traffic is _____ sight.

6. _____ the same time, CAir 035 receives a TCAS “climb” RA.

7. _____ fact the pilot continued _____ descend.

8. The pilot continued to descend _____ accordance _____ ATC avoiding instructions.

9. Always correct errors and insist ______ correct readback.

10. Monitor flight crew compliance ____ RTF callsign use.

Exercise 9.3.12 Make up sentences using the given words.

1. climbing/ he/ to/ is/ FL 90/

2. not/ the/ notice/ pilot/ that/ does/ incorrect/ callsign

3. descending/ the/ FL 096/ aircraft/ pass/ at/ 1,5 nm/ both/ apart

4. climb/ the/ clearance/ pilots/ further/ of/ expecting/ CAir 035/ were

5. abbreviated/ the/ CAir o35/ of/ that/ fact/ his/ the/ pilot/ callsign

6. times/ use/ all/ correct/ at/ RTF/ discipline/ at/ phraseology/ and/ procedures

7. ACAS/ avoidance/ provides/ collision/ the/ of/ most/ means/ effective

8. Appropriate/ he/ as/ should/ information/ provide/ traffic

9. Constraints/ recognize/ and/ working/ and/ understand/ pilots’/ the/ understand

Exercise 9.3.13 Translate the following sentences into English.

1. Самолет пытался произвести посадку в аэропорту.

2. Несколько минут спустя пилот сообщил, что он набирает эшелон 90.

3. Диспетчер выдал неправильное разрешение.

4. Борт уже прошел эшелон 90.

5. Фактически пилот все же продолжал снижение.

6. Запрос относительно дальнейшего снижения был искажен, позывной был нечетким.

7. Пилот ожидал разрешение на дальнейшее снижение.

8. Пилот сократил свой позывной, что привело к ошибочному пониманию.

9. Используйте постоянно правильную фразеологию радиообмена и процедуры.

10. Передача может быть заблокирована, если два или несколько экипажей реагируют на одно и то же самое разрешение.

11. Диспетчеру не стоило пытаться изменять (модифицировать) траекторию полета.

Exercise 9.3.16 Retell the text.