Carroll McCormick explains how a solar-powered runway lighting and NAVAID system guarantees reliability at an airport in Mogadishu.
Faced with the need for night-time flights, yet unable to rely on a conventional supply of power, the United Nations (UN) specified a solar LED runway lighting solution for the Aden-Adde International Airport (formerly the Mogadishu International Airport). It also purchased a solar LED Abbreviated Precision Approach Path (APAPI) to assist inbound pilots.
The elapsed time from the awarding of the contract to the certification of the installed system was just four months.
Built by the Italians in the 1940s, according to one source, and renamed in 2007 after Aden Abdulle Osman Daar, Somali’s first President, the Aden-Adde airport has seen far better days. Although there is a new terminal building in good condition, other structures have been torn down and sold for scrap. The runway has suffered tsunami damage. Jackals trot across the runway into scrub that grows over its edges. Empty edge lighting cans, the remnants of threshold lighting foundations and destroyed PAPI lighting bases are about all that remain of a once-functioning airside lighting system.
Despite the infrastructure damage, the airport handles 300-400 flights a month by the UN, military air arms and five commercial carriers. Since support for the African Union Mission in Somalia (AMISOM) troop contingent stationed there is projected to increase over the next two years, the UN determined that it was necessary to make the airport capable of handling night-time operations. “The security situation on the ground makes it much safer to move military, medical and humanitarian relief in at night,” reports Benjamin Folger, the President of Gossamer Crossing, based in Carson City, Nevada, USA.
Gossamer Crossing carries out development and construction, and provides security in support of humanitarian and disaster relief organizations in Somalia. It submitted the winning bid in response to a UN Request for Proposal (RFP) for a variety of infrastructure improvements at the Aden-Adde airport, including a solar runway lighting system.
The UN has years of experience with solar-powered airport and obstruction lighting equipment, says Allister Wilmott, Director, ARC Aviation Renewables Corp, based in Victoria, British Columbia, Canada. “The United Nations has used solar light-emitting diode (LED) runway lighting in Sudan and [solar LED obstruction lighting] for towers in East Timor, Mexico, Africa and even solar wind cones in Haiti and elsewhere.”
There was just about every reason under the sun not to install a conventional, cabled lighting system on the airport’s sole runway 05/23, which is 10,564ft (3,220m) long by 148ft (45m) wide: the unreliability of the local power grid and the problem of getting adequate power for the airport; the high cost of producing power from a generator; the long installation time and far higher cost of a cabled runway lighting system, compared to a portable solar solution; the higher cost of maintaining a conventional system and the lack of technical expertise to service it.
A solar-powered LED lighting system, on the other hand, has none of these disadvantages. Installation takes just hours, the power comes from the sun, the lighting units are maintenance free and the LEDs are rated for 100,000 hours.
After winning the contract to install the lighting system and carry out other infrastructure improvements, Gossamer Crossing contacted Flight Light Inc, a Sacramento, California-based distributor of airport lighting for Avlite Systems and partner of Aviation Renewables. Flight Light, in turn, contacted Aviation Renewables. In addition to its consultation services for solar LED lighting and off grid power solutions, Aviation Renewables also designs custom solar power operating systems using aviation products obtained from a variety of manufacturers.
The solar runway lighting for the Aden-Adde airport was a straightforward, off-the-shelf solution: Gossamer Crossing ordered solar LED taxiway and runway lights manufactured by Victoria, Australia-based Avlite Systems, through Flight Light (see details in sidebar).
“Avlite is a world class manufacturer of civil, defence and humanitarian aid solar airfield lighting solutions, and has the most extensive solar airfield lighting product suite available,” Wilmott says.
The AV420-RF runway edge and threshold lights meet ICAO Annex 14 lighting requirements, have infrared capability and are remote controlled. “The infrared LED option was required in both the solar LED APAPI and AV420-RF lights for military aircraft flying on night vision goggles,” Wilmott explains.
Because of the low power consumption of the LEDs, the lights have more than 200 hours of standard-intensity autonomy; ie, the number of hours it can operate without recharging.
The solar LED APAPI was custom-designed by Aviation Renewables and Laser Guidance Inc, the manufacturer of the LED APAPI system. Laser Guidance is located in Redmond, Washington, United States. Solar Electric Supply Inc, based in Soquel, California, helped designed a frangible solar-powered system that conforms to international aviation regulations.
A lead-acid gel battery system gives the solar LED APAPI seven days of autonomy. This ensures safe, effective operation, performance in poor weather and availability in periods of high demand.
The design, consultation and inter-manufacturer collaboration took about 30 days and an additional two weeks to deliver the equipment to Mogadishu.
The most exotic challenge of the whole project was working in Somalia. Folger describes the challenge in just getting the system shipped to Mogadishu. “We used air freight to get the lights to Mogadishu from Australia and the APAPI from Arizona. There were many, many delays in shipping as local carriers waited for return loads of product such as camel meat. There were also delays due to mechanical issues with aircraft. The carriers that service Mogadishu are operating in a tough climate.”
In the run-up to the installation Folger emailed this update: “The guys are on the ground, having a rough couple of days, vehicle was arrested and our work camp confiscated. Not unusual but takes a bit of time and arrangements to resolve.”
Gossamer Crossing is used to working in Somalia, and Folger is comfortable with the way things are done there. “We do have our own security and yes, we could have refused to surrender the worksite. However, as we are guests and the ground is controlled by AMISOM the correct thing to do is let AMISOM take control and work it out in meetings.
“Somalia is a really fun place to work due to the wide open way that business is conducted and the options for getting things done. There are some security risks, but the main challenge is just the pace at which business gets done in that region.”
Work crews poured concrete bases in the sand alongside the runway on which to mount the two LED APAPIs, the power control unit and the frangible solar system. Using an inclinometer, which is included in the package as standard equipment, Gossamer Crossing’s installation technician adjusted each of the LED APAPI’s three legs to obtain the optimum glide slope, and then locked them. This procedure takes as little as two minutes once the basic concept is mastered.
It was simplicity itself installing the LED taxiway, runway edge and threshold lights: “We built a custom template based on the base plates supplied by Avlite. At each previously located light position, we pulled the hardened nail that was marking the location and nailed the template precisely over that spot. We used a rotary hammer to drill four holes in the asphalt for each plate. Then we removed the template and aligned
a base plate with the holes. We screwed in expansion bolts. We set each light, with its frangible coupling, over the base plate and aligned it with the runway,” Folger explains. The crew adjusted some settings on the lights and remote controller to complete the installation. The sun does the rest.
Gossamer Crossing began installing the APAPI, taxiway and runway lights last November 1. The UN Support Office for AMISOM tested and certified the system and declared it operational on November 15, 2010.
The lighting system has:
• 12 blue Avlite AV70-RF taxiway lights;
• 63 white Avlite AV420-RF runway edge lights;
• 38 yellow Avlite AV420-RF runway edge lights;
• 12 red/green Avlite AV420-RF threshold lights.
• Avlite remote controllers
The NAVAID system has:
• 2 Laser Guidance Solar Series LED APAPIs
• 1 Solar Series Solar Electric Supply frangible MAPPS