On October 16, 1972, Congressional Leader Hale Boggs of Louisiana and Congressman Nick Begich
of Alaska mysteriously disappeared on a charter flight between Anchorage and Juneau. The search for Boggs and Begich was expansive, involving 90 aircraft dispatched on 1,000 flights. The search area encompassed 326,000 miles of Alaskan wilderness. President Nixon instructed the Air Force to include the powerful SR-71 in the search. The Mach 3 Blackbird is capable of cranking through 10,500 feet of high-resolution film in a single sortie. From 80,000 feet, it can cover a great deal of real estate in a short period. None of it was enough to discover the final resting place of the Cessna.
Early in his political career, Hale Boggs had participated in the Warren Commission inquiry into the assassination of JFK. After his death, there was idle speculation that he had been killed by the mafia over his opposition to the single shooter theory. Nick Begich’s widow, Peggie, added fire to the mob motif when she quickly wed a leg breaker named Jerry Pasley. Pasley was a bartender from
Tucson who had links to a semi-retired mob boss named Joe Bonanno. Peggie and Jerry’s courtship took a couple of months. The marriage lasted a little bit longer. By 1994, Peggie had long moved on and Jerry Pasley was in jail for murder.
A couple years into a life sentence, Pasley reached out to the FBI looking for a deal. He claimed that Peggie had met covertly with Joe Bonanno a month prior to her husband’s disappearance. Pasley also asserted that he had delivered a package to Alaska “the size of a bomb” on behalf of Bonnano. He surmised that Peggie had wanted Nick Begich killed in order to collect on a large insurance policy. He scurrilously claimed that Peggie had been involved in several affairs prior to Begich’s death.
Under questioning, Pasley had no answer for how Peggie would have gotten mixed up with Joe Bonanno. Neither could Pasley explain how the mob would have known to go after N1812H (the accident aircraft). The charter had been a last-minute affair. Nick Begich himself had not known the tail number prior to the flight. Pasley had the hallmark of a lifer trying to con his way into a reduced sentence. He had eight felony convictions, including two each for murder, kidnapping and aggravated assault. He was not a credible source. His babble was duly recorded and cataloged for the conspiracy theorists.
From Implausible to Probable
In aviation, there is something more menacing than the mob. It starts at 32 Fahrenheit and only ceases to be dangerous once a decreasing thermometer throttles moisture from the atmosphere. It ruins airflow over wings and disrupts the ability of propellers to produce thrust. It has caused innumerable accidents throughout the history of aviation. Icing can be remarkably dangerous. We are forced to deal with it while living on the shivering side of the equinox.
The pilot of the charter flight was Don Jonz (feeling that “Don Jones” was too bland, he had opted for a more singular surname). Jonz was the president, chief pilot and sole shareholder of Pan Alaska Airways. Jonz possessed substantial experience in icing conditions (unsurprising for an Alaskan bush pilot). With tragic irony, he had written a magazine article about ice just prior to the accident. The article was published in Flying Magazine two weeks after N1812H had vanished. It was pithy with some good pointers: icing encounters occur predominantly around 0 Celsius; a change of a few thousand feet is generally enough to exit icing conditions; never accept a hold at an altitude where ice is accumulating, etc. Unfortunately, Jonz also drifted into bravado: “Be wary of pilots who say [that flying into ice] can’t be done. They can’t…If you don’t like ice, stay the hell out of IFR.”
Though the specifics may vary, compo-nents protected against ice are generally uniform across different aircraft types. 
In the event of equipment failure, do not fear. Maintain sufficient airspeed and establish an exit strategy.
The chartered Cessna 310C was sparsely equipped. Only the pitot tube was protected against ice. Certification rules were an odd animal in the early 1970s. Part 135 regulations had been around for less than a decade, and they did not yet provide guidance for operation into known icing conditions (rules pertaining to the aircraft were nonetheless still applicable). Within a year of the crash, new regulations were developed for light aircraft operated under Part 135.
Jonz’s flight plan took him through Portage Pass, a valley bounded by mountains. V-317 traced a line through the area with a MOCA of 8,000 feet. Two hours before Jonz was due to traverse Portage Pass, an Air Force helicopter turned back due to low ceilings and severe turbulence. Terminal and area forecasts indicated moderate rime ice between 6,000 and 15,000 MSL. Jonz bragged multiple times in his posthumous article about successfully traversing areas of ice without the need for deice equipment. A good guess is that Jonz set off towards Portage to take a peek. Facing bad turbulence and deteriorating visibility (with a couple congressmen in the back), a climb to a safe IFR altitude had to have sounded like a good idea.
The Right Tools for the Job
Ice protection is a multi-system affair on modern aircraft Flight into Known Icing (FIKI) equipment provides protection for the windshield, leading edge of the wings, engine intake, and pitot-static system. Propeller-driven aircraft are generally equipped with heated propeller boots as well. There is a good argument that this is the most important piece of equipment on a turboprop. A fouled prop does a poor job transferring power into torque.
Props are generally heated via a brush block and slip ring. An amp gauge indicates proper operation of the system. If the amps drop, at least one propeller boot has failed (this can generate an imbalance on the affected side as ice causes one blade to weigh more than the others). If the amp gauge indicates zero, the brush block is no longer in contact with the slip ring (none of the props will be heated). On most twin-engine aircraft, the system cycles between different propeller pairs to reduce total electrical load requirements. The amp gauge must be monitored over a period of time in order to ensure that the different sequences of heaters are working.
In general, turning on prop heat is better done earlier than later. If you wait until a quarter of an inch is on the prop before activating the system, you will inevitably startle passengers with the iterant thuds of shed ice slapping the fuselage (applicable to wing-mounted engines). Before long, the paint perpendicular to the prop arc will be sanded down to bare metal. More concerning is the fact that even small amounts of ice can dramatically decrease thrust. This condition can be prevented by the immediate application of prop heat (turn it on when entering the clouds below 5 Celsius).
Jet pilots aren’t off the hook. Fan blades are not any better with ice than props, though they are somewhat more resistant to accumulation. In a jet, the presence of ice will manifest as an abnormal vibration on the affected engine. Cycling the thrust lever is typically enough to shed the offending ice. As always, follow the type-specific guidance on your particular aircraft. It is a good idea when gearing up for the winter months to review cold weather guidance contained in the operating manuals. Don’t get caught by surprise.
Ice in the Real World
In 2009, I was a brand new captain flying a Beech 1900D between Denver and Cheyenne. Snow showers were present at both airports. It was a short hop, and we were in icing conditions the entire flight. Descending into Cheyenne, the clouds became thick enough that I had a hard time seeing the leading edge of the wing. The airplane felt sluggish. I suspected that we were trucking around a substantial amount of ice. I flew the aircraft faster than was technically allowed, adding 10 knots to our approach speed.
The aircraft stalled a few seconds into the flare. There was no buffet or aural warning. We were 30 feet above the runway when the bottom simply dropped out. We left a divot in the touchdown zone following the hardest landing I ever had. Once it was shut down, I inspected the airframe. The wings were caked in a couple inches of ice. The ice was in the shape of an inflated deice boot. During the last few minutes of flight, the deice boot had been inflating inside a hollow block of ice. This particular phenomenon is referred to as bridging.
Bridging is a touchy subject. The NTSB dismisses it, contending in 2007 that “It [has been] established that ice bridging does not occur.” The FAA is more nuanced, noting that bridging can occur with older deice boot systems. Both the NTSB and FAA are unanimous in their conviction that waiting for a predetermined amount of ice to accumulate before “blowing the boots” (a technique ostentatiously used to avoid bridging) does more harm than good. Their position stems from this: “Since 1982…43 icing occurrences involving turbine-powered airplanes…have resulted in 201 deaths and 16 serious injuries.” None of the accidents were attributed to bridging. Several were associated with the failure to activate deice boots in a timely manner. The FAA encourages pilots to activate deice boots as soon as ice begins accumulating.
In truth, the operation of deice boots – while important – is secondary to maintaining sufficient airspeed. I had been reluctant to fly 10 knots faster than the published approach speeds (which already included a few knots to account for ice accumulation). In hindsight, I should have added 20 knots. A month after my event, a crew made an approach into Salina, Kansas. They encountered severe ice on final. The pilots reported windshield wiper arms encased in ice the size of baseball bats. They maintained 170 knots throughout the approach (40 knots above normal speeds). They only slowed once they were committed to landing. The aircraft touched down without incident. When the cabin door opened, it hit a six-inch cone of rime on the prop spinner. When ice is hanging off the airframe, speed is life.
Severe ice requires an immediate change in altitude to exit the conditions (continuing an approach in many cases is better than climbing back into the offending environment). Many aircraft manufacturers publish speed increments to be added during an approach in icing conditions. Technologically advanced aircraft automatically adjust stall margins when ice is detected by advancing the AOA of stall alert systems. Many modern aircraft automatically activate ice protection as soon as ice is detected. Certification guidance has, over time, adapted to ensure better safety margins. For all of this, many tried-and-true pilot techniques are still applicable.
Maintain sufficient airspeed. Occasionally turn off the autopilot in order to “feel” the aircraft. If it feels sloppy, go faster. Do not allow airspeed to degrade in order to maintain altitude. If you cannot maintain adequate speed, descend. Consider declaring an emergency to obtain ATC priority. Modern aircraft produce relatively stable stall characteristics when clean. On a contaminated airframe a stall can be sudden, asymmetric, and occur out of the blue. Snap spins can materialize without warning if airspeed degrades below safe ice speeds.
Fly Fast
On February 16, 2005, two Cessna Citations approached Pueblo Memorial Airport in Colorado. The sister ships were owned by Circuit City. They were flying from Richmond, Virginia, to Santa Ana, California. Both aircraft were scheduled for a short fuel stop in Pueblo, where IMC and freezing drizzle prevailed. Pueblo tower was vectoring inbound traffic for the ILS. The Citations were equipped with stick shakers programmed to alert seven percent in advance of stall speed. The aircraft had been retrofitted with an AOA computer, which added another five knots to stick shaker speed when engine anti-ice was selected to ON. The inboard wings and engine cowlings were protected against ice via heated surfaces. The outboard wings and horizontal stabilizer were protected by deice boots.
Only one deice boot activation was captured on the accident aircraft during the approach. The sister ship recorded five separate activations during their own approach (which took place 30 minutes after the accident). The sister ship carried excess airspeed throughout the approach, hustling through 1,500 feet AGL at 160 knots (they remained above 120 knots until descending below 200 feet). The accident Citation was decelerating through 98 knots at 1,500 feet – 62 knots slower in the same atmospheric conditions. The accident crew failed to reference ice accumulation speeds provided by Cessna during a truncated approach briefing. The first officer on the accident flight made an ambiguous reference to both the icing conditions and the decaying airspeed seven seconds before the aircraft entered a sharp roll. Six seconds following the initiation of the roll, the aircraft crashed.
At the time of the accident, deice boot procedures were on the NTSB’s ten most wanted list for aviation safety. As such, it was not surprising to see the final report spend a substantial amount of time on the topic. In the end, the failure to activate the boots was not the primary cause of the accident. The failure to carry proper airspeed was. The appropriate ice reference speeds would have afforded the crew a 20-knot safety margin throughout the approach. On a long runway, a few excess knots would have been permissible as well. Although icing speeds are established to protect against max continuous ice accretion, the margins above stall may be less than what pilots are normally afforded. An additional fudge factor for a difficult approach can be appropriate in some circumstances.
When encountering ice, pilots must maintain a psychological balance between terror and boredom. There is no reason to be intimidated by ice. Still, a healthy dose of respect is called for. In truth, most ice encounters are relatively benign and can be safely traversed even in non-FIKI equipped aircraft. You should obviously not fly into icing conditions without properly functioning equipment, but do not panic if you find yourselves in those conditions inadvertently (or following equipment failure). Find a safe exit while maintaining sufficient airspeed.
Though fear can be a debilitating emotion when dealing with airborne threats, a blasé attitude is no better. Even properly certificated aircraft are not capable of managing anything more than light ice indefinitely. It is always a good idea to find another altitude when ice is encountered, no matter the intensity. A few thousand feet up or down is generally enough to exit the conditions. It does not take a ton of ice to be dangerous. A minimal amount of ice accumulation can dramatically increase stalling speeds, decrease propeller efficiency and increase drag. There is no such thing as a safe amount of ice, only a safe margin of airspeed. Be brave, but also be fast.
