Questions & Answers
Q. Gireesan M – Gooseneck, we call it
A. Yes. This is the name usually given to equipment (that often looks like a watering can with a wick)
Q. Tony Vaz – Would it be possible to show the formula for a PAPI install?
A. I suggest that you download the TMS Webinar which deals with this. The guidance provided by ICAO is over-complicated and does not optimise ILS / PAPI harmonisation. The fundamental parameter is wheel height at the threshold, not the eye height. In the webinar we showed that all aircraft can be harmonised down to flare initiation.
Q. Sebastian Sobecki – Current standards ICAO/EASA/CAP168 don’t mention solar powered fixed lights, how are those seen by regulators in terms of compliance e.g. power. Will there be an update to cover this technology?
A. My opinion is that solar powered lights could be acceptable for Precision Approach Category 1,2,3, but only if they have the intensity / beam characteristics specified in Annex 14. However, as I established before I retired this type of equipment can provide a useful service for night-time operations where 50 candela can provide the necessary guidance with very simple light patterns.. This is a suitable subject for some research but I think it is outside the remit of the ICAO Visual Aids Working Group.
Q. Jyothi Prasad – The approach light length as per ICAO is 900 mtrs, while as per all weather operations manual the FALS is 720 mtrs. can you please clarify?
A. 900m was required to properly support Category 1 operations (800m RVR/200ft DH) in the 1960’s. More recently it has been established that with improvements in the lighting specifications and non-visual systems it is feasible to reduce some of the original operating limits. This can safely be done by lowering the RVR limit or reducing the length of the approach lighting pattern but not both. I suggest the options are, (A) retain 900m pattern length and reduce the RVR minima or (B) retain the RVR limit and reduce the pattern length. There is a choice but you cannot have both (A) and (B) and still retain well-established safety levels.
Q. Rajesh Nair – What is CAT I & CAT III serviceability criteria for Sequence Flasher lights?
A. I think the same level of output (70% minimum, requires servicing) should apply.
Q. Sebastian Sobecki – Is the 3 minute PAPI toleranse for the transition of colour or set up of the angle . ADM part 4 states that angle discrepancy of more than 1 minute should eb adjusted.
A. Overall, a signal tolerance of 3 min is specified, which implies transition and setting accuracies should be less than 3 minutes, so that the total tolerance comes within the 3 minute tolerance criteria
Q. Len Ellchuk – Can you please provide information about harmonization of PAPI glideslope wit ILS systems by increasing from 20 minutes to 30 minutes.
A. We generally have P2 systems but have seen an advisory circular where going to 30 minutes is best for P3 only.
The 30 minute sector is not normally required unless very large aircraft (e.g. 747, A-380) are being operated.
Q. Jyothi Prasad – Can localizer be installed just before the 300 mtr cross bar?
A. For more information on ILS please refer to this document: Instrument Landing System (ILS).
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