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Webinar 9 Q&A

Q1How often should you clean runway lights and what cleaning method is most effective?The frequency of cleaning will vary from airport to airport depending on conditions e.g. traffic and weather conditions.

The best method for cleaning is to use a MALMS Cleaner as part of your system of planned preventative maintenance.
Q2We have recently installed LED lights and noticed some lights randomly flashing, What could be causing this?This is a scenario experienced on various airports and will depend upon several things:

1) When you installed the LED fixtures to replace the TH, was this done without replacing the CCR. If you have a Thyristor based CCR then the load value has lowered dramatically and you must re-calibrate the tap settings on the CCR to reflect the new circuit load values. Flashing LED lights could be experienced specifically at the lower intensity setting if this has not been completed.

2) Whose model of LED lights have been installed? Some of the modern LED lights available are known very simply as "Smart lights" which incorporate the capability for ILCMS operation. These utilise technology call PWM (Pulse Width Modulation) and there may be incompatibility between the AGL circuit components such as the CCR?

3) Have you checked the Insulation resistance values on the specific primary circuit. Again dependent upon circuit component s and light fixture supplier, the poor IR values, and potentially intermittent earth faults could cause this phenomenom. Only detailed knowledge of your installation & types of installed components, the suppliers of the lighting fixtures and model of the CCR's etc can this question be answered fully !
Q3ICAO states the frequency of measurement of lights for a Cat II or III runway should be twice a year for in-pavement lights and not less than once a year for other lights, so why do more?ICAO Annex 14, Chapter 10.5 states "The frequency of measurements of lights for CAT II / III runway should be based on traffic density, local polution level, reliability of the installed lighting equipment and the continuous assessment of the results of the in-field measurements". It then says "this should not be less than twice a year". However, in our experience this is never sufficient to maintain serviceable lighting. Best practice requires monthly testing but many airports test weekly. TMS are happy to work with individual airports to evaluate requirements on a case by case basis.Robert S
Q4What are the operational safety issues that arise when the runway lighting output is significantly lower than that specified by ICAO and why is a flight inspection not sufficient to ensure compliance with the specifications?One of the key design requirements for the approach and runway light is that during an approach and landing the pilot should receive consistent visual cues. Operationally this means that once a pilot making an approach establishes visual contact with a segment of the lighting that is sufficient for the safe execution of the final phase landing the size of that segment must be maintained and usually increased as the approach continues to a landing and roll-out. If the runway lighting is badly maintained (values below 10% output are encountered) then there is the dangerous possibility of the pilot experiencing a rapid decrease in the visual segment late in the approach (sometimes called the black hole effect). Visually, especially at night, this reducing segment can seem to the pilot as an indication that the pitch attitude of the aircraft is increasing and as a result this can result in the pilot making a control movement to lower the nose of the aircraft and land short of the runway. This lack of runway light output has been documented as a cause of landing accidents.

There is documentary evidence of runways where the lighting output was less than 10% being flight inspected and passed as serviceable. Human sight does not find it possible to detect large differences in light output unless the change is accompanied by a significant colour change so photometry needs to be employed in any inspection.
Q5ICAO document Annex 14 requires average intensities inside the inner ellipse of the relevant iso-candela diagrams of 20,000 cd for approach lights, 10,000 cd for runway edge lights and 5,000 cd for runway centreline lights. Why are the intensities not the same for all lights?See the answer to Q 4. The ICAO iso-candela and setting angle lighting specification were developed to provide the operationally required lighting cues, During development of the systems it was found that the specified intensities, beam dimensions and setting angles in Annex 14 meet the operational requirement to provide useable and reliable visual cues. Enshrined in the specifications are important considerations; the intensity required reduces as the viewing range decreases, it must practicable to provide the required lighting bearing in mind optical, engineering and power supply issues, there must not be abrupt changes in the intensity a pilot sees and the lights must not be as source of discomforting or disabling glare. Tony
Q6Should in-service monitoring be carried out on all types of AGL equipment? For example should approach lights and illuminated signs be tested?Yes. Every part of the AGL provides essential information to pilots and therefore needs to be maintained on the basis of appropriate monitoring.Tony
Q7Is the 70% serviceability level for AGL fixture maintenance mandatory?
eg. as shown in the photometric results bar charts (ie. shown as the blue sector)
No … the 70% serviceability level in the ICAO operational theatre is NOT mandatory ! The 70% was chosen to reflect a level of serviceability between the ideal 100% and the failure level of 50% so that maintenance/servicing is performed BEFORE the failure level is reached! Airports can decide their own level of serviceability as to when such servicing needs to be commenced. One MUST REMEMBER though, when selcting a different "serviceable level" away from the suggested 70%, it is incumbent on Airports to demonstrate their AGL serviceability if their approved & certified Category of Operation is to be maintained.Keith
Q8What should the photometric output compliance standard be for AGL light fixtures after servicing in the workshop and before they are re-used in the field? eg. 100 % or some other?Ideally, the target for serviceability after servicing in the workshop should be as close to the 100% serviceability level for a new or fully functioning fixture. Again, it is for the airport to decide what level is accptable following workshop maintenance. Remember, the lower % serviceability level you select after servicing will mean that the deterioration rate back down to the 70% maintenance level in the field will be quicker and hence more field replacements & access will be required ??Keith
Q9In the MALMS Engineer/Dashboard Asset Management System, can it monitor and record other maintenance functions other than those currently described:
• Photometrics : PAPI’s; Guidance Signs; Apron Floodlighting
• Electrical : Insulation Resistance; CCR faults
• Civils : Runway Friction; Pavement Surface Condition
We are currently integrating MALMS Engineer and MALMS Dashboard with the new
Apron Tester (Luxometer) and Sign/PAPI Tester products. Dashboard panels showing recent test data and status will be available along with historic reporting.
On the electrical side it is already possible to create CCR and IR inspections in MALMS Engineer. Insulation Resistance inspections include the possibility of entering readings taken in Megaohms into the tablet. The dashboard reporting then allows trends and tabular data to be produced along with current status and dashboard warnings on non-compliance.
Civils is already a big part of MALMS Engineer. Non-asset faults can be reported and logged such as pavement issues, FOD, security issues and obs lights. Runway friction readings could be entered on the tablet as part of an inspection and the values monitored from the dashboard.
Rob B
Q10What will be the recommended chemicals or solutions to be used for the inset light cleaning without damages to rubber gaskets aluminum housings and also protect to human?

Asoka Leelarathne
TMS reccommends the use of Bicarbonate of Soda for fast and effective removal of rubber, de-icing fluid, paint and other contaminates. This biodegradable and environmentally friendly powder will not contaminate the light fitting, there's no thermal shock as with dry ice, no water ingress as with steam or water jet and no scratching from brushes. Bicarbonate of Soda is used by MALMS AGL Cleaning Machines and is used with other MALMS systems to support an airports planned preventative mainteance. For further information please visit our website ( Paul
Q11In which chapter of ICAO is clearly indicates the minimum servicibility levels for each catogary? But as I remember and according to our Manufacture more than 50 % is accepted?

Asoka Leelarathne
The 50% requirements are in Annex 14, Appendix 1, Collective note 8. This note explains that at 50% a light is “out of service” and that in practice much higher levels of output should be achieved.Tony
Q12Could you describe the procedures of chromaticity measurements of TGS boards, and what would be the passing ranging of candela for TGS?

Sekar Balakrishnan
Information on the requirements for sign luminance (not intensity) and chromaticity are to be seen in Annex 14, Section 5.4 and Appendix 4 and in ADM, Part 4 Chapter 11.Tony
Q13How do we do photometric test for approach lights?

Cheng Fai Chan
Approach lights may be tested in the workshop using a MALMS photobench. In-field testing for inset and elevated fixtures up to 1m high can be measured using MALMS Mobile. Higher elevated approach lights may be tested using the MALMS static measurement device and require a scissor lift or similar to raise it to the required level.Robert S
Q14My question is related to ICAO requirements of average beam intensity and unserviceability of lights

10.5.1 describe beam intensity as minimum 50%

10.5.15 describe percentage of number of unserviceable lights

My question is when we are talking about intensity , Are We need to maintain the system over 85% , 95% ,,,?

Asoka Leelarathne
There are 2 aspects to consider:
1) an individual light fixture
2) the AGL as a system eg. a Runway Centreline or a Runway Edge as a system.

1) An individual light fixture: ICAO define a light to be unserviceable when its average main beam output falls to 50% of the value described in the appropriate Isocandela diagram in ICAO Annex 14 Volume 1. For this, we are describing the Isocandela diagram INNER sphere.... see Annex 14 Vol 1 Iso candela diagrams (Each type of lighing fixture eg Runway Edge or Approach light etc has its own Isocandela diagram). The average value is determined by selecting the number of one (1) degree grid points that cross each other within the inner sphere, measuring the photometric output at each 1 deg,. crossover point, adding them all together and then dividing by the number of crossover points within the inner sphere. This gives the average mean value of the light output. This is based upon feeding the light fixture at the maximum 6.6 amps (known as 100% light inrtensity).

2) The AGL as a System: ICAO desribe sytem serviceability in ICAO Annex 14 Vol 1 Chapter 10. It describes system servcieability dependent upon the Catagory of Operation eg. CAT I & CAT II/III

For CAT I: There must be 85% of lights in each system that are serviceable (ie. above 50% intensity for each light unit) and no two (2) adjacent lights unserviceable. eg. If you have a 2400 metre runway then, for Runway edge lights placed at 60 metre intervals, you will have 2400/60 = 40 lights down each side making 80 lights in total for the runway edge system. Therefore 85% of 80 lights is 68 lights. Hence only 12 lights can be unserviceable and no two (2) adjacent light unserviceable. Also remember , the lights as a system comprisies two (2) circuits (interleaving).

For CAT II/III: There is a different % of serviceablity for each system in CAT II/III with the maximum % being 95% serviceability ( some system requirements are lower then 95% ... see Annex 14 Vol1 Chapter 10.). HOWEVER, for maintenance purposes we recommend that you adopt the 95% serviceability level for ALL systems when operating for CAT II/III + no two (2) adjacent lights are to be unserviceable in any system in CAT II/III operations.
Q15Rob, in MALMS report, where can we see the servicibility chart for a specific light with CAT II RWY?

Mohamed Nawar Rehawi
The Photometric Perfomance chart is available from the Dashboard in two places.
Firstly if you are running an Isocandela report for a single lamp chosen from a Course Bar Chart, a link is available in the bottom right corner of the report. Secondly from the Map View, click an asset and choose the 'trend' button. This will produce the graph report you require.
Rob B
Q16How to check photometric test for PAPI light?

Chandramohan Narayanan
The test criteria for a PAPI are setting angle, transition, colour and intensity and the only commercially available device for in-field testing is the MALMS Sign & PAPI Tester.Tony

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