The Impact Of The Harmattan Weather On Aviation Operations In Ghana
Aviation, probably more than any other mode of transportation, is greatly affected by weather. From thunderstorms to reduced visibility due to hazy conditions, every phase of flight has the potential to be impacted by weather. Commercial aviation in the West Africa, must deal with these adverse types of weather regularly, and the cost is a significant budget item. One of the perennial weather phenomena that have adverse impact on flight is the hazy condition known as Harmattan.
The Harmattan is a cold-dry and dusty trade wind, blowing over the West African subcontinent. This northeasterly wind blows from the Sahara Desert into the Gulf of Guinea between the end of November and the middle of March. The Harmattan blows during the dry season, when the subtropical ridge of high pressure stays over the central Sahara Desert and when the low-pressure Intertropical Convergence Zone (ITCZ) stays over the Gulf of Guinea.
The low visibility condition brought about by the Harmattan, poses a significant safety hazard as pilots have to stretch their skills and proficiency to land in such conditions.
Ghana has a relatively fledgling domestic aviation market, which is constrained by high tariffs, high fuel cost, relatively low load factor and limited routes. A typical domestic operator’s Direct Operational Cost (DOC) per flight can range between $2500 for a regional jet type aircraft with seating capacity of 50-70 passengers to Kumasi and $3000 for a similar flight to Tamale. Direct costs due to weather on airline operations can be separated into several categories: diversion, cancellation and delay.
The direct costs sometimes are eclipsed by the cost of rub-off factors. The costs listed are from a variety of areas, some fixed and then others not: fuel, crew time, aircraft operating costs, lost passenger and cargo revenue, ground-based employee overtime pay. In 2014, there were 4,072 domestic flights to Tamale and 8070 flights to Kumasi. The highest domestic movements were in April (Tamale: 388 and Kumasi: 860).
The lowest movements were in November/December (292 flights to Tamale and 560 flights to Kumasi). Even though there may be other variables, obviously the effect of weather may have a significant impact on these reductions and the economic effects on domestic operators cannot be downplayed (GCAA, 2015).
Though the costs associated with delays and cancellations vary, airlines taking such actions risk eroding passenger goodwill and that results in lost future revenue. The impact goes beyond just the lost revenue from ticket sales. The list includes added costs for rescheduling crews, including transportation and hotel costs.
Even if the plane doesn't take off, the airline still incurs maintenance cost to get it ready and stock it with food. Ticket agents still show up for work to deal with stranded passengers at the gate. Even though an argument could be made that airlines save on fuel and landing fees from flights that never took off, there are still issues with crew that were on standby, rescheduling of passengers, and repositioning of aircraft. Ground crews still need to shuffle schedules and try to get planes back where they were headed before the cancellation.
Those costs can range from about $2,700 an hour for a carrier operating a regional jet according to masFlight Consultancy and cumulatively lead to loss of millions of dollars in a market where profit margins are rare.
The severe Harmattan weather adversely affect operations to Kumasi and Tamale Airports. The irony is that Tamale airport is yet to be upgraded with a precision approach system, such as an Instrument Landing System (ILS) that will provide precision guidance for pilots to land in such low visibility conditions.
Recently there were pomp and pageantry during the commissioning of the rehabilitated aeronautical ground lightening system at the Kumasi Airport by the President of Ghana. Strangely, the ILS which was supposed to be functional has not had the requisite procedure for use by pilots officially charted in the Aeronautical Information Publications (AIP) of Ghana by the Ghana Civil Aviation Authority (GCAA). That makes the use of that ILS ‘Illegal’, discretional and a safety hazard due to ambiguity of procedures.
The advantages of having navigational aids like an ILS and approach light components at Kumasi and Tamale is that it provides precision vertical and horizontal navigation guidance information during approach and landing. The attractiveness of ILS lies in the economy of its avionics costs and its wide international acceptance. Technological advances over the years have yielded great improvement in accuracy, dependability, and maintainability.
An approach may not normally be continued unless the runway visual range (RVR) is above the specified minimum. When an approach is flown, the pilot follows the ILS guidance until the decision height (DH) is reached. At the DH, the approach may only be continued if the specified visual reference is available; otherwise, a go-around must be flown.
Normally the standard for the basic category 1 ILS is a DH of 200 feet above runway threshold elevation (ARTE) and RVR of 550 metres (with touchdown zone and centerline lighting) or 800metres visibility. The installation cost of a typical Category 1 ILS may range between $1. 75 Million –$1.87 Million and an operations/ maintenance tag of about $105,000 adjusted for inflation in 2015-dollar figure (ACI, 2008).
Other options that are available to operators in Ghana are Performance Based Navigation (PBN) procedures such as the Area Navigation (RNAV), Required Navigational Performance (RNP) based approach, and other Wide Area Augmentation Systems (WAAS) certified terminal procedures.The WAAS will allow Global Navigational Satellite Systems (GNSS) such as the US Global Position System (GPS) and European Union EGNOS to be used as a primary means of navigation from takeoff through Category I precision approach.
The advantage of WASS lies within an increased accuracy, availability, and integrity. Other advantages of WAAS are the efficiency of aviation operations due to, new precision approach services, reduced and simplified equipment on board aircraft and significant government cost savings due to the elimination of maintenance costs associated with older, more expensive ground-based navigation aids.
However, the operators should have WAAS enabled navigational equipment on board their aircraft, and the crew should be proficient and authorized to use WAAS enabled equipment and approach procedures. There should also be a mechanism to ensure reliability and integrity (Receiver Autonomous Integrity Monitoring).
Another viable option will be a Ground-Based Augmentation System (GBAS) system that provides differential corrections and integrity monitoring of Global Navigation Satellite Systems (GNSS). GBAS provides navigation and precision approach service in the vicinity of the host airport (approximately a 23 nautical mile radius), broadcasting its differential correction message via a very high frequency (VHF) radio data link from a ground-based transmitter. GBAS yields the extremely high accuracy, availability, integrity necessary for Category I ILS. GBAS has several advantages in comparison to traditional ILS.
One GBAS station can support multiple runway ends and reduce the total number of systems at an airport. This reduces the Very High Frequency (VHF) requirements and simplifies airport infrastructure. The GBAS approach guidance is steadier than ILS approach guidance. In addition, GBAS requires less frequent flight inspections compared to those required of ILS systems.
A recent study by the navigational service provider ASECNA in Dakar (Leopold Senghor International Airport) in 2013, estimated the Net Present Cost (NPC) of a GBAS installation over a 15-year span would be 7.5 million Euros. The initial capital expenditure was estimated at 4.6 million Euros and operational expenditure of 272,000 Euros.
The ILS on the other hand will have a NPC of 6.9 million Euros and capital expenditure of 3.3 million and operational expenditure of 346,000 Euros. Even though the GBAS had a higher capital expenditure, due to the low operational cost, the NPC was similar, with reported economic benefits for GBAS exploitation within 5-6 years.
The effectiveness of these navigational infrastructures will be constrained if there is inadequate meteorological support. The era of human estimation of visual range is becoming a past time and we need to equip the Ghana Meteorological Agency with RVR measuring systems. The system measures visibility, background luminance, and runway light intensity to determine the distance a pilot should be able to see down the runway.
Each RVR system consists of the following functional elements: Visibility Sensor, Ambient Light Sensor, Runway Light Intensity Monitor, Data Processing Unit and Controller Display(s). Other essential components that will be needed to enhance the capability of aircraft operators to land in low visibility conditions are Approach Light Systems (ALS), which provides the basic means to transition from instrument flight to visual flight for landing.
Operational requirements dictate the sophistication and configuration of the approach light system for a particular runway. For Tamale and Kumasi due to the initial capital expenditure and operational expenditure, at a minimum a MALSR (Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights) is recommended.
MALSR is a medium approach intensity lighting system (ALS) installed in airport runway approach zones along the extended centerline of the runway. The MALSR, consisting of a combination of threshold lamps, steady burning light bars and flashers, provides visual information to pilots on runway alignment, height perception, roll guidance, and horizontal references for Category I Precision Approaches.
The biggest caveat with all these systems is that their reliability and integrity depends on uninterrupted power supply and the ability to detect internal faults within very short periods. Hopefully the necessary investment will be made to enhance the growth of domestic aviation in Ghana.
Okatakyie Kwasi Adjekum @ kadjekum@yahoo.com
Sources:
ASECNA: CNS/SG/5/IP/06 Fifth Meeting of the APIRG Communications, Navigation and Surveillance Sub-group (Nairobi Kenya, 16-19 September2013) Feasibility Studies on Ground Based Augmentation System (GBAS).
Airport Council International (ACI): http://www.aci.aero/Media/aci/file/2008%20Events/Safety%20Seminar%202008/Speakers/day%202/Dr%20Sean%20XIAO%20ILS%20Replacement.pdf
Federal Aviation Administration (FAA): http://www.faa.gov/documentLibrary/media/Order/8400.13.pdf,
FAA NEXT-GEN Navigation https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/waas/,
Ghana Airports Company Limited : http://www.gacl.com.gh/airports_2.html
Ghana Civil Aviation Authority: http://www.gcaa.com.gh/extweb/docs/erd/Domestic%20Aircraft%20Movement%20Distribution.pdf
ICAO ANNEX 6, ICAO ANNEX 10 Vol 1, Chapter 3.
The Fiscal Times: http://www.thefiscaltimes.com/2015/03/03/Badr-Weather-Flight-Cancellations-Cost-Americans-24-Billion
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