AOOA Aviation Safety Forum
AOOA AVIATION SAFETY FORUM
Presented by Richard Jeffery, September, 2022
Download the document in PDF Format here.
Re : Minor Aerodromes of Zambia, their standards, proper use, and aircraft suitability
Motivation for preparing this aviation safety forum paper concerning the Minor Aerodromes of Zambia and their proper use and suitability for different types of aircraft and purposes comes from recent safety reviews and observations among our most experienced senior pilots and engineers in the industry.
Of course I have no monopoly over facts vs fiction, but I have spent some months over this year talking to a number of our most seasoned professional pilots and engineers about this topic, and it seems that there are indeed too many instances of aircraft owners and operators using classes and types of aircraft (sometimes unwittingly) on unsuitable airstrips that do not meet minimum standards of safety or common sense. This poses risks to lives and property, including chronic and acute damage to aircraft, and it may be no coincidence that there has been a notable number of light aircraft incidents and accidents over recent years specifically in relation to the use of so called “bush airstrips”.
There are not many but some among our ranks who are not inclined to take this matter too seriously, and it is to those individuals in particular that I simply say, pay attention.
Airfields or Airstrips (referred to in this paper just as “Airstrips”), under the broader categories of Aerodromes and Airports, are regulated by the Zambia Civil Aviation Authority (ZCAA) through the Zambia Civil Aviation Regulations or ZCARs. This paper in particular looks at the use of Minor Aerodromes by both Private and Public Category (commercial) aircraft, by nature mostly restricted to the smaller fixed-wing aircraft, and which have limited landing and parking areas with un-improved or partially improved surfaces of variable composition and quality, and limited passenger handling and safety facilities.
It is understood that all such Airstrips in Zambia must be Registered and Licensed according to the current compliance requirements and implementing standards of ZCARs. As a helpful guide only, because there is currently no other such formal reference, Figure 1 is a copy of the original DCA’s minimum specifications[1] for such Airstrips.
Meanwhile, current regulations do not specify minimum dimensions or aircraft restrictions, instead there is the understanding that any owner or operator of such an Airstrip must ensure the design and construction meets ZCARs’ compliance requirements such as they are, and publishes the facility’s specifications in order that any aircraft owner or operator may determine if any particular aircraft type may perform safely into and out of the airstrip concerned.
After recent meetings with the CAA, the AOOA understands that the CAA is similarly concerned that all such Airstrips meet or exceed the safety standards required for their use by private and public category (commercial) aircraft, and are equally concerned that aircraft owners and operators themselves are adequately trained and experienced to determine an aircraft’s suitability for the airstrips they intend to use.
This of course puts the discretion on both the airstrip and aircraft owners and operators, but, while we may enjoy this flexibility, if we do not exercise this privilege judiciously, we may expect more incidents and accidents to occur and more explicit regulations to be imposed.
The AOOA is therefore keen to make all airstrip and aircraft operators more aware of the required minimum standards and performance specifications of minor aerodromes, and the hazards associated with their use or mis-use.
We might expect small private airstrips to have reduced specifications where intended for use by microlights, crop spraying or other STOL aircraft not requiring more exacting standards, provided that the airstrip’s restriction to such types of aircraft is duly noted. However, if the airstrip is expected to be used by larger aircraft and public category operations (ie for paying passengers), then more advanced specifications and higher standards would be essential for the safety of both private and commercial flights to and from such airstrips.
There are very good reasons for such provisions, and particularly for normally maintaining or exceeding minimum specifications. Nearly a century of experience has shown that for the light charter aircraft industry, the following airstrip dimensions are sensible minimum requirements for such operations, but even then would be restricted to aircraft with adequate performance under prevailing conditions, including aircraft payload, runway surface dimensions, quality and elevation, and surface conditions such as temperature and winds, etc.:
Runway Length (useable) 1,200m
Runway Width (useable) 30m
Runway Length Overruns 60m each end (2 x 60 = 120 m)
Runway Width Clearways 45m each side (2 x 45 = 90 m)
Total Airstrip Length 1,320m
Total Airstrip Width 120m
Parking Area (minimum) 30m x 30m 900m2
Therefore, the following critical factors must crucially be reviewed before even considering using any minor aerodrome in Zambia, or elsewhere, by a Zambian registered aircraft:
Is the Airstrip registered and licensed, open and serviceable?
Aircraft size, mass and performance
Airstrip runway length, width, over-runs and clearways, surface quality, condition,
obstacles and obstructions
Airstrip maneuvering and parking areas and their surface quality, condition, obstacles and obstructions
Weather conditions including surface winds, temperature and rainfall
Experience of flight crew
When considering safely useable limits in terms of runway surface and condition, information regarding sandy, clay, gravel, prostrate grass, clumpy grass, long grass, and concrete and asphalt surfaces must be assessed. Furthermore, assessments of whether or not the runway surface is soft, clammy, flooded, wet, skiddy, rutted, lumpy, rocky, stony, or uneven are all additional critical factors in determining an Airstrip’s suitability for any particular aircraft. Similar considerations must be assessed for the maneuvering and parking areas of the Airstrip.
When considering safely useable limits in terms of the potential for an aircraft egressing the Runway on to its clearways or over-runs also needs to be assessed, whether due to short and/or narrow runways, high temperatures and Density Altitudes, variable surface winds and cross winds, tyre-bursts, un-intentionally deep landings, take-off and go-around power losses (including SE Vmca performance for MEL aircraft), people, game animals or birds on or in the vicinity of the Airstrip, obstacles and depressions such as termite mounds, holes and drainage furrows, trees, powerlines, towers, buildings and other infrastructures, etc.
Airstrip suitability assessments should consider restricting the use of some Airstrips to certain classes and types of aircraft with performance characteristics that match or exceed the Runway specifications, particularly if the Runway dimensions are lower than the specified minima, but which may be adequate for some smaller SEL and certain STOL MEL aircraft.
It should be noted that both piston- and turbine-powered MEL charter aircraft, even those with professed good short-field performance, and especially the larger types, are either unlikely to or unable to attain a safe IAS above their Vmca until well after take-off from airstrips less than 1,200 m, which means that any engine power loss during and immediately after a take-off run or go-around is likely to end in an incident or potentially serious accident at any airstrip below these minima. If you have not thought of this as a MEL pilot, it is about time you did.
Putting all this information and associated factors together, it is clear that for the sake of Airstrip length or width extensions in the order of a few hundred meters here or there, the cost of which would be negligible compared to the benefits of providing the public with safer Airstrips of more than adequate dimensions and quality, there can be no doubt that we must do better for all our most important airstrips in Zambia, especially those licensed for commercial air service operations.
It is understood that the CAA has already initiated such a review of the licensing of minor aerodromes and airstrips in Zambia with a view to improving their safety and quality while ensuring that compliance requirements are not unreasonable, overwhelming or financially disabling. The AOOA suggests that the industry should be engaged with the CAA in this process, particularly the non-scheduled commercial (public category) air charter industry which is most affected by exposure to using minor aerodromes below acceptable specifications and standards.
As for the pilots themselves, we bear a heavy responsibility, private or commercial, in ensuring that we exercise the privileges of our command with care, common sense, and due regard for operating within the limits of aircraft and aerodrome performances and specifications.
We can all make “honest” mistakes of course, and I’ve had my fair share of moments of poor airmanship, but there is no place in the industry for such wilful bravado as “… yes the runway was a bit short, we only just made it out scraping over the trees, even picked up a few leaves on our tailskid, but we made it, no problem …”! I beg to differ, that is a problem.
Owners and operators of “bush” airstrips should equally beware of pretending that their airstrips are “…perfectly fine, we’ve had lots of different and larger aircraft in here with no problem at all …” when this is clearly a convenient but dangerous exaggeration of the facts and reality.
There are many such airstrips in Zambia, more particularly some of the more heavily used “commercial” airstrips with specifications that should sensibly restrict their use to smaller single-engine or certified STOL aircraft, a position more or less unanimously shared among the majority of serious experienced pilots I have recently consulted on this issue.
In fairness to all pilots, they may also be under pressure from the aircraft or airstrip owners to do these flights, even if they are not comfortable with them, because they may be persuaded it will give them a competitive edge in a tough industry. But this is not a good thing at all, and owners and operators must listen to and respect their pilots’ reservations and safety judgements when expressing concern over the use of minor or marginal Airstrips.
[1]Civil Aviation Act CAP 444 No. 13 of 1994, replaced by ZCARs under the Civil Aviation Act No. 5 of 2016