[redcoat]

Minimum Radar Separation on final approach: Provided there is no danger of wake turbulence, the minimum radar separation provided between aircraft established on the same localizer course shall be not less than;

My answer 3.0 NM

Database answer 2.5 NM

ICAO 4444 answer

13.4.2 A minimum of 300 m (1 000 ft) vertical or a
minimum of 5.6 km (3.0 NM) radar separation shall be
provided between aircraft during turn-on to parallel ILS
localizer courses and/or MLS final approach tracks.

13.4.3 The minimum radar separation to be provided
between aircraft established on the ILS localizer course and/or
MLS final approach track shall be:

a) 5.6 km (3.0 NM) between aircraft on the same ILS
localizer course or MLS final approach track unless
increased longitudinal separation is required due to
wake turbulence; and

b) 3.7 km (2.0 NM) between successive aircraft on
adjacent ILS localizer courses or MLS final approach
tracks.

[Baz]

Hi,

ICAO Doc 4444 Para 8.7.4.2 (b)
4.6km (2.5 NM) between suceeding aircraft which are established on the same final approach track within 18.5km (10NM) of the runway end.

BGS notes page 222.

Baz

[jon h]

I've been quite confused by these separation on final questions. Indeed it is possible for the separation to go down to 2.5NM, "subject to runway occupancy times etc" as the BGS notes put it. Doc. 4444 lays down a number of conditions for this to be allowed:

7.4 Radar separation minima
7.4.1 Unless otherwise prescribed in accordance with
7.4.2, 7.4.3 or 7.4.4, or Part IV with respect to independent
and dependent parallel approaches, the horizontal radar
separation minimum shall be 9.3 km (5.0 NM).
7.4.2 The radar separation minimum in 7.4.1 may, if so
prescribed by the appropriate ATS authority, be reduced, but
not below:
a) 5.6 km (3.0 NM) when radar capabilities at a given
location so permit; and
b) 4.6 km (2.5 NM) between succeeding aircraft which
are established on the same final approach track
within 18.5 km (10 NM) of the runway end. A
reduced separation minimum of 4.6 km (2.5 NM) may
be applied, provided:
i) the average runway occupancy time of landing
aircraft is proven, by means such as data collection
and statistical analysis and methods based on a
theoretical model, not to exceed 50 seconds;
ii) braking action is reported as good and runway
occupancy times are not adversely affected by
runway contaminants such as slush, snow or ice;
iii) a radar system with appropriate azimuth and range
resolution and an update rate of 5 seconds or less
is used in combination with suitable radar
displays; and
iv) the aerodrome controller is able to observe,
visually or by means of surface movement radar
(SMR) or a surface movement guidance and
control system (SMCGS), the runway-in-use and
associated exit and entry taxiways;
v) wake turbulence radar separation minima in 7.4.4
below, or as may be prescribed by the appropriate
ATS authority (e.g. for specific aircraft types), do
not apply;
vi) aircraft approach speeds are closely monitored by
the controller and when necessary adjusted so as to
ensure that separation is not reduced below the
minimum;
vii) aircraft operators and pilots have been made
fully aware of the need to exit the runway in an
expeditious manner whenever the reduced
separation minimum on final approach is
applied; and
viii) procedures concerning the application of the
reduced minimum are published in
Aeronautical Information Publications.

This particular question makes no mention of these special conditions. Also, the passage above makes no mention of "localizer". I believe the appropriate regulations in this case are those quoted by Redcoat, and I suspect the answer, "2.5NM" is based on a misunderstanding of the regulations.

If I am correct this would explain why the answer 3.0NM is the only one on offer in the following question:

Q1916
Question: The minimum radar separation to be provided to aircraft established on the localizer course shall be: 3.0 NM between aircraft on the same localizer course.

Info:You can only choose one of the four answers offered; you can't write a fifth answer because you think it is better.

In this case a better answer would have been 2.5nm but as it's not present, 3nm is the best available.

Also on this subject, in this thread we are asked to accept that two practically identical questions are intended to have different answers. I read, "with additional longitudinal separation as required for wake turbulence" as referring to the regulation, "(3.0 NM) between aircraft on the same ILS localizer course... unless increased longitudinal separation is required due to wake turbulence". I do not accept that 5.0NM is a reasonable answer and I believe in both cases the answer should be 3.0NM.

I am due to be examined on this subject next week and I have no confidence that the answers provided to these questions are actually correct. I would appreciate any advice.

[Baz]

The minimum separations are:
2? nm between two aircraft on the same localizer course
or
2 nm between two aircraft on adjacent localizer courses approaching parallel runways.

Q12041:
Minimum Radar Separation on final approach. The minimum radar separation provided between aircraft established on the same localizer course shall be: (plus additional longitudinal separation as required for wake turbulence)

Answers offered are 2, 2?, 3 or 5 nm. Correct answer 2? nm.

Q1916:
The minimum radar separation to be provided to aircraft established on the localizer course shall be:

Answers offered are:
3.0 NM between aircraft on adjacent localizer course. Wrong - it can come down to 2 nm
5.0 NM between aircraft on the same localizer course. Wrong - it can come down to 2? nm
2.0 NM between aircraft on the same localizer course. Wrong - 2 nm is not enough
3.0 NM between aircraft on the same localizer course. Best answer so far. since answers are all to the nearest mile, not ? mile, this is the examiner's prefered answer.

Baz

[Flyting]

why we need to worry about this sort of thing when we are under radar control I don't know.... let the ATC do his/her job.......

study hard learning all the questions everyone

[jon h]

Other sources give different answers to some of these questions, for example:

http://academy.antalyava.org/info/AirlawATC.pdf

The following minimum radar separation shall be provided between aircraft on the same localizer with additional longitudinal separation as required for wake turbulence:
a 2 NM.
b 3 NM. <
c 5 NM.
d 2.5 NM.

The minimum radar separation to be provided to aircraft established on the localizer course shall be:
a 3.0 NM between aircraft on adjacent localizer course.
b 3.0 NM between aircraft on the same localizer course. <
c 2.0 NM between aircraft on the same localizer course.
d 5.0 NM between aircraft on the same localizer course.

Which radar separation minima is applicable between succeeding aircraft established on the same final approach track within 10 nm of the runway?
a 2.5 nm. <
b 3 nm.
c 4 nm.
d 5 nm.

Which wake turbulence radar separation minima shall be applied between a HEAVY aircraft and a succeeding MEDIUM aircraft during the approach and departure phases of a flight.
a 2.5 nm.
b 4 nm.
c 5 nm. <
d 6 nm.

Note the first two questions ask about "same localizer", the third question asks about "same track within 10nm" and has a different answer to the first two. The question asking about wake turbulence gives the wake turbulence categories necessary to answer that question.

[Baz]

What is the source of these questions ?

[jon h]

There's a link to the source at the start of the quote above. Appears to be taken from a database of questions simliar to the QB.

[Dick W]

Seems to be a Turkish company, Antalya.va, .va meaning .co ltd, as .sa in spanish means sociedad anonima

Similar, but not quite the same!

Dick

[Baz]

Ref the four questions posted yesterday by Jon H:

Q1: correct answer is (d) 2.5nm, not (b) 3.0nm.
Q2: correct answer is (b) for reasons I have given above.
Q3: I would go for answer (b) 3.0nm because the questions states "on the same final approach track" not "on the same localizer".
Q4: correct answer is (c) 5.0 nm wake turbulence separation for MEDIUM following HEAVY.

Baz