Of Anvil Heads & Wall Clouds:
Storm avoidance strategies for a long- hot summer.
Have you noticed the weather lately? It’s certainly been a spring for the record books in the US – and it impacted flight operations. Unusually wet storms from the Mississippi River Basin and points west- north and east – the Ohio River Valley – have produced flooding of historic proportions after the storms battered parts of the country with impassable weather.
Floodwaters continued to overflow river basins- adjacent American neighborhoods normally far removed from Tornado Alley found themselves on something akin to a Twister Turnpike. Tornados are seasonal- but this season has been overactive by a factor of two – killing more than 520 and devastating cities and towns from Kansas to Massachusetts! Beyond arriving early- this dangerous- convective weather looks as determined to overstay its welcome as a casino buffet guest at closing time.
To cap it all- prognostications from leading meteorological authorities predict a well-above-average level of activity in hurricanes spawned and spun off from the West African desert. Conditions as active and diverse as these play badly for aviators and aircraft unfortunate enough to encounter them – in-flight or on the ground.
Mother Nature often dishes out a stew of “don’t-go-there” conditions - a witches brew- if you will- that can simultaneously produce the violent- airframe-rattling convective weather of summer and that bane of winter aviating - airframe icing - even when ground temperatures exceed the century mark. Such conditions should bring into focus the true meaning of three little words in the aviators’ lexicon:
One Sun ‘n Fun Fly-In in Lakeland- Florida- a half-dozen pilots and aircraft owners (this writer included) gathered in wonder at what we’d just seen on a tour of the commercial exhibit area: a stretch of airport landscape littered with battered- broken- crinkled airplanes of a wide variety.
“It’s conditions like these that give truth to the words- ‘weather avoidance equipment-’ quipped a retired check airman and corporate pilot in our group. He’d just learned his client’s propjet survived the destruction because the hangar it occupied survived (the north side of the field had escaped the brunt of the storm). Several dozen airplanes parked on the Fly- In grounds - several of them vendors’ exhibit stock hadn’t been so lucky.
“Had you noticed those five or six airplanes that bailed before the line arrived?” the former corporate jet captain asked. “They left like trains on the same rails. Now that’s ‘weather avoidance’. They wanted to avoid even a slight prospect of a clash with the elements- and they won.”
Tragically- despite significant signs- existing tornado and severe-storm watches and continuous storm coverage perfected by The Weather Channel and countless local stations- too few people paid any apparent attention to the prospect of the miniature Armageddon approaching Lakeland Linder Regional Airport from the west.
No one died - relatively few needed treatment for injuries - but the storm stopped air traffic across an area of thousands of square miles- and wreaked havoc on those dozens of airplanes at Sun ‘n Fun that year.
Elsewhere in the nation- similar casual treatment of impending-weather warnings contributed to the unusually large number of deaths- as did the urban impacts of the worst tornados. So why do so many still not consider it a big deal? Treating dangerous weather as an inconvenience to be managed can send a flight beyond inconvenient- to uncomfortable and even outright dangerous.
For pilots- the smart use of weather avoidance information opens several decision paths. A look at the variety of weather avoidance tools and how they help inform may ease the pain of explaining an inconvenient decision to a cabin occupant in a hurry.
THE IMPACT OF THE WRONG DECISION
Weather statistics dating back years reveal a fairly consistent level of fatal accidents characterized as weather-related – somewhere between one in seven- and one in six. The bulk of these came from the non-business majority of General Aviation flying and equipment.
Business-turbine aircraft- crew and passengers- have been subject to weather they would have preferred avoiding- though. Perhaps the crew of a flight running late received an incomplete or abbreviated weather briefing prior to finding inhospitable conditions en route or at the destination. Others may have spotted the problems before passing beyond the airport fence but proceeded anyway. Still others might have encountered weather issues when trying to take a look for a runway- despite weather accurately reported to be below minimums – and even farther below the company’s own operations guide.
Sometimes the only correct solution to the threat of weather is not to fly the mission at all. At other times- it means diverting around the weather- or simply delaying the flight to travel after the problem-weather has passed.
Whichever of the above avoidance techniques works best- flight crews are blessed with more weather information and weather-avoidance tools than ever before- and there is no excuse not to plan around dangerous weather. Where the aircraft and its safety are concerned- the captain has the final say and has the more intimate knowledge of conditions and its potential than any novice with an iPhone- iPad- XM Weather or 4G feed of The Weather Channel.
Some slack is in order for any captain or crew member who raises the topic of delay or cancellation. It’s the crew’s job – and it’s their lives- too.
TOOLS OF THE (AVOIDANCE) TRADE…
The single-most important tool on the flight deck of any aircraft works from a perch just behind and above the control yokes: the brain of the pilot-in-command.
The hours logged to earn a place in the cockpit of most business-turbine aircraft not only includes the basic training- but also specific- demanding training to fly in inclement weather- as well as specific training in the airplane flown. Those hours of training experience- working and talking about work with other aviators produces a body of specialized institutional knowledge- knowledge about different regions and different seasons.
Only through experience can a pilot develop as a flyer who knows when to fold- when to divert- when to wait – and that is thanks to- mostly- unsuccessful judgment calls already survived. We learn from experience; we gain experience through making – and surviving – many a small mistake and even a few larger ones. It’s that knowledge tool that makes the other tools useful- among which are the ` following:
FAA Weather Information: This can come from the Flight Service Station network- the online flight-briefing service DUATS- as well as sundry free government websites. One favorite amongst aviators is http://aviationweather.gov. Many other pay sites exist. Irrespective of the ultimate delivery source however- the bulk of the data used is sourced from government sensors.
Datalink Weather: Popular among many pilots who own and use devices capable of receiving XM Weather via a portable or installed cockpit device. Sent by satellite- these broadcast services include virtually all the information available from the government- but are updated every few minutes for cockpit consumption. (Datalink weather is also available via the Flight Information Service-Broadcast system operated by the FAA and transmitted via ADS-B – again- to cockpit receivers for viewing on a display screen.)
Airborne Weather Radar: Standard equipment on virtually all business jets and available on most propjets- today’s airborne weather radar is digital- Doppler and shown in colors specific to the manufacturer’s system. Shortcomings include interpretation issues and signal attenuation by nearby storms severe enough to render the image untrustworthy.
Spherics Devices: A fancy word for “lightning detectors-” today’s latest and most-sophisticated sensors and delivery systems can even display the strike data in colors that vary according to intensity- frequency and concentration.
Mk.IIEB System: The old- smart-enough-to-not-be-bold pilots know that the Mark II EyeBall System can detect weather issues that the experienced brain can process – without consulting a weatherman.
CARE & FEEDING OF AVAILABLE DATA
If you ask 100 pilots what they’d do in a certain set of weather-related circumstances- their answers would likely vary according to their equipment. For example- a pilot flying an aircraft equipped with radar- spherics and weather datalink may answer with a higher degree of willingness to press forward and take a look before retreating.
A pilot flying with only one of the above three will likely exercise a degree of comfort that extends only as far as the sensors can see – showing caution for everything else. Today’s modern business-turbine pilot will probably have at least two- if not all three avoidance technologies. But these sources work only when believed and respected. No amount of data can overcome a pilot willing to succumb to performance pressure of a passenger eager to get home.
“Don’t worry- Honey- we’ll get home in time for Tanya’s recital- one way or another-” the passenger promises his wife. That’s not as healthy a response as- “Don’t worry- Honey- we won’t fly if it isn’t safe. I’ll watch the video of Tanya’s recital then.” One response increases the odds of a safe reunion; the other only increases the odds of an unhappy- unhealthy encounter.
Again- we emphasize: the crew are the experts. They’re hired for their expertise. When the captain says- “We’ve got convective weather that we might get through- but waiting would be better-” the “might get through” part isn’t the invitation to go- regardless. It is the captain’s way of saying- “The smart choice is to stay put…agreed?”
It’s a feeling that’s the root of the old aviator’s adage: “Better to be down here wishing you were up there- than up there wishing you were down here.” Had they known the depth of their troubles- the flight crew of Air France 447 surely would have shared that sentiment- while questioning their decision to continue flying toward a broad swath of convective weather a few hundred miles out of Rio de Janeiro…
Ditto for the turboprop airliner crew making an approach in severe icing- and the propjet regional airliner crew who accepted a lengthy hold in extreme icing conditions years ago over Indiana.
Accidents are typically the outcome of a long cascade of mistakes- most of which set off mental alarms long before the failure finally struck. Urging a captain to “take a look” at the under-minimums approach may make one sound knowledgeable – “We did that last time and it wasn’t bad…” – or it may make you dead.
More than once a business aircraft crew tried to squeeze out a few more feet – only to find a small altimeter error showed them higher than they actually were. In reality- an altimeter can legally show enough error to put you 75 feet closer to the ground than indicated.
Pressures exist in the corporate cockpit – the pressure to not “let the boss down-” or to “get the folks home to their families-” or to complete the charter mission without incurring any profit-ravaging delays. There can be many justifications for a delay- a cancellation- or a diversion - but none are more justifiable than a decision to avoid subjecting the plane and its occupants to possibly life-threatening weather.
Think about it: Surely it’s better to be a pilot who’s late than a late pilot…
ASRS Weather’s ripple effect:
ASRS Weather Encounters: http://asrs.arc.nasa.gov/docs/rs/63_ASRS_GA_WeatherEncounters.pdf
IBAC Woodhouse report: http://www.ibac.org/Files/Safety/Woodhouse_Report_V11.pdf
‘US VERSUS THEM’
Many a time sitting as a back-cabin passenger a fellow flyer has muttered something about the weather “excuse” for the delay. “That private plane was allowed to go…” they might observe. There are differences in how we can treat weather decisions- and they’re largely as simple as the type of operation. For Part 91 pilots- those flying private planes for private purposes- trying – shooting – and approach is legal regardless of the ground visibility.
They may fly as low as minimums for a quick peek. For commercial operators- whether charter or scheduled under Part 135 or Part 121- such trial-and-we-hope-no-error attempts are not allowed.
Only if visibility reports come in above the published minimums – a hard-and-fast- black-and-white rule violated at everyone’s risk. So- before even beginning an instrument approach- commercial air-carrier pilots – like their private counterparts – check the latest weather reports to be sure the approach planned has conditions above minimums. Even starting the approach from the initial approach fix is a violation when conditions are below minimums.
As noted above- numerous reasons exist for never attempting an approach in below-minima conditions – it’s more than a dumb idea… It’s dangerous and illegal.
For one thing- ILS signals don’t always have the same signal strength. Glideslope signals may suffer from distortion close to the ground while others may barely fall within specifications at decision height – and- from decision height to the ground can be wholly unreliable and inaccurate. Additionally- glideslope signals can be distorted by heavy snow and rendered unsteady in heavy rain.
Let the heading be off a couple of degrees- throw in a calibration error in the receiver- fail to get the correct altimeter setting… and you’ll have no guarantee that you’ll find a runway before the ground finds you.