Expected Approach Time (EAT)

EAT is the time at which ATC expects that an arriving aircraft, following a delay, will leave holding point to complete its approach for a landing.

Note.— The actual time of leaving the holding point will depend upon the approach clearance

 An expected approach time shall be determined for an arriving aircraft that will be subjected to a delay of 5 minutes or more.

The expected approach time shall be transmitted to aircraft as soon as practicable and preferably at first contact.

A revised expected approach time shall be transmitted to aircraft without delay whenever it differs from that previously transmitted by 5 minutes or more.

EAT is issued to ;

a) enable the pilot-in-command to determine whether to divert without delay or to hold;

b) enable the pilot-in-command to position his aircraft to take advantage of a final approach/instrument approach clearance without delay;

c) enable the pilot-in-command to decide whether to absorb a specified period of notified terminal delay by cruising at reduced speed en-route or not;

d) form a basis on which action subsequent to a radio failure will be adopted.

Initial approach clearance or holding instruction shall include an EAT if it is estimated that an aircraft will be required to hold at the holding point before it comes its final approach.

EAT and approach sequence shall be based on the ETA over BTF VOR/DME or SH NDB/LOC.

For the purpose of uniformity for calculating EAT, the following items should be taken into consideration :

Case 1 : When the first aircraft is able to descend directly to 3 000 feet over BTF VOR/DME or SH NDB/LOC :

a) EAT for the first aircraft which is not subject to delay will be specified as : NO DELAY EXPECTED;

b) EAT for the second aircraft will be ETA of the first aircraft over BTF VOR/DME or SH NDB/LOC added by the average time interval (ATI);

Note 1.— Average time interval (ATI) is the time duration taken by aircraft from the commencement of instrument approach until the last time the aircraft is expected to establish visual contact.

Note 2.— In calculating EAT for the second aircraft, time of entry of the first aircraft shall be considered;

  

Note 3.— ATI for :

a. VOR approach runway 16R is 7 minutes (derived from the flying time using speed 120 – 125 knots   4 DME = 2 minutes and 9.16 DME = 4 minutes and 30 seconds = 6 m 30 s rounded off upward = 7 minutes); and

b. ILS approach runway 34L is 6 minutes (derived from the sum of outbound time of base turn + turning + inbound time to SH NDB/LOC then plus flying time from SH NDB/LOC to DA/H).

c) EAT for the second aircraft will be ETA of the first aircraft added by the ATI and EAT for the subsequence aircraft will be the EAT of the preceding aircraft added by ATI (see figure 9 below).

Figure 9. EAT calculation for Case 1.

Case 2 : When the first aircraft is unable to descend directly to IAL but maintain at specified level until BTF VOR/DME or SH NDB/LOC (on reaching BTF VOR/DME or SH NDB/LOC the aircraft is able to descend to 3 000 fee).

a) EAT for the first aircraft which is not subject to delay will be pecified as : NO DELAY EXPECTED;

b) EAT for the second aircraft will be ETA of the first aircraft over the BTF VOR/DME or SH NDB/LOC added by the elapsed time of descent from the specified level to 3 000 feet and then added again by the ATI;

c) EAT for the subsequent aircraft will be EAT of the preceding aircraft added with the ATI (see figure 10 below).

Figure 10. EAT calculation for Case 2.

Case 3 : When the first aircraft is unable to descend directly to IAL but maintain at specified level until the departure/en-route aircraft has reached 5 minutes out of holding area (en-route aircraft is maintaining 1 000 feet below the arriving aircraft) :

a) EAT for the first aircraft will be the time of the en-route aircraft estimated to be 5 minutes out of holding area;

b) EAT for the second aircraft will be EAT of the first aircraft added by the elapsed time of descent from the specified level to IAL and added again by the ATI;

c) EAT for the subsequent aircraft will be EAT of the preceding added with the ATI (see figure 11).

Figure 11. EAT calculation for Case 3.

Speed assignment for aircraft proceeding from holding fix

Considering that one of the objectives of practical exercise is how to implement all types of separation contained in the Doc. 4444-501/AN – Air Traffic Management, it is necessary to re-arrange the speed

assignment for aircraft proceeding from holding point (BT/TF NDB) to IAF (BTF VOR/DME or SH NDB/LOC) in order to have the flying time 7 minutes or more.