Winter weather requires vision
By Johan Lottering
AFTER payday some develop 'vision problems' and stay away from work. The thing is they just can't see themselves working. Likewise, lack of vision can ruin the day for aviators. Winter weather phenomena necessitate insight and farsightedness. The hazy world between VMC and IMC ensnares many. If it were only a matter of complying with AWOPS criteria accidents would be cut in half. Remember the JFK Jr. Accident? He failed to anticipate smoke haze would be trapped in the middle air layers shortly after dark. Tired and under self-induced pressure, he became disoriented without reference to a visual horizon.
The Transport Safety Board of Canada Study 90-SP002 analyzing a seven-year period preceding 1982 showed roughly half of all 'VMC into IMC accidents' were fatal. The study referred to US NTSB statistics in the corresponding period showing 72 percent of fatal weather related accidents occurred in the recreational milieu. Before saying 'they should not have died for fun', bear in mind the same study also found 27 percent fatal VMC into IMC accidents involved charter operations. Then buy a chopper to 'stay below the clag'? MaybeÖ But, the study showed 27 out of 33 fatal accidents associated with 'whiteouts' involved only one case where the pilot was instrument rated. Back then the Canadian TSB already advocated the cultivating of better decision making skills to deal with 'marginal' or 'changeover' conditions.
A sunny VFR day in winter can also ensnare us. VFR conditions generally require five km flight visibility and a ceiling of 1500 feet above ground level. Ceiling is the base of the cloud layer covering more than half the sky below 20,000 feet. According to AIC 40; 01-09-15 Special VFR clearances can be requested in Control Zones when two-way radio contact can be maintained and conditions equal or better than 1500 meters forward visibility and a 600 feet ceiling exist. So, where's the catch?
On January 16, 2013 an Augusta A109E collided with a construction crane near Vauxhall Bridge on the Thames River to kill the pilot and a pedestrian. In South Africa the same ill-fated guy would be looking out for muggers instead. Nonetheless, the CLIENT had been the one sending cell phone text messages to the pilot not to take-off from Redhill till he's assessed the weather at destination Elstree. Notwithstanding, the pilot took off and flew himself into a deadly situation, trying to 'work around' prevailing marginal weather, using 'Special VFR'.
With 'Special VFR' bear in mind you are likely to encounter delays and need to make fuel endurance allowances. ATC cannot accommodate two aircraft in the entire Control Zone at the same time. The 'rationale' is that whilst conducting a Special VFR flight, the pilot needs to be able to circumnavigate clouds and obstacles at own discretion complying with clearance to 'stay in sight of ground and clear of cloud'. IFR traffic will take preference. Bear in mind smoke, mist and fog can often be seen through whilst directly overhead an aerodrome, whilst on final approach the runway can disappear from view, due to the slanted range, or 'oblique visibility'. Fog and mist often form AFTER a pre-dawn actual weather report has been obtained. Look at the tendency! Instructors and radio examiners alike ought to pay special attention to these often ill-considered aspects of flight.
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