I once flew into a box canyon on purpose.
A friend of mine lived in a canyon between Pacific Palisades and Malibu on the southern California coast. He’d introduced me to a powerful men’s weekend retreat and it course corrected my life. That one retreat helped me achieve the dream of becoming a pilot, and so when I got my helicopter license, I decided to give him a view of his home like he’d never seen it.
He accepted the gift. That day, we departed Torrance Airport to the east instead of to the west due to strong easterly winds. Temperatures were also unusually high for December.
Southern California pilots recognize this as a Santa Ana condition — hot winds pouring out of the mountainous desert into the bowl that is LA County — and they would pay particular attention.
I, on the other hand, was paying more attention to impressing my highly accomplished, millionaire friend with the one skill I had that he didn’t — commanding a helicopter to do my bidding.
Twenty minutes later, we had crossed under the KLAX approach paths, buzzed the surf alongside a few beaches and flown over KSMO. A few minutes after that, we made a right climbing turn into the mouth of a narrow box canyon — his home canyon. I was fully aware of what I was doing. I was flying a narrower, R-22 helicopter, so I didn’t see a problem.
It was a treat to witness how thrilled he was to be flying over his street, well up the incline and finally above his house, near to the hills. I tried to bring us into a hover, but no amount of control inputs would keep us in one spot. Before he might notice there was a problem, I just eased us into a slow circle around his property. What I began to realize after a handful of turns was our inability to maintain altitude. We were slowly sinking.
I motioned to my watch to indicate time to go. Then I tried to fly up and out of the mouth of the canyon. No go. Santa Ana downdrafts pouring off the near vertical terminating cliff were overpowering our little Robinson. Things didn’t look good. I kicked 180° and tried to climb into the wind, straight at the canyon. Also no go. We didn’t sink, but we didn’t climb much either. Then I remembered my training.
I turned back around, away from the canyon walls, flew a few yards and then circled back toward the canyon. That gained me a few feet. So I did it again. I flew tight little 360s, ascending a few feet for every revolution until I was above the canyon ridge and free of the Santa Ana’s grip.
Thankfully, while I sweated that out, my oblivious friend thought we were just having more fun over his neighborhood.
I learned three powerful lessons that day. First, even a strong headwind won’t overcome high density altitude in an underpowered trainer aircraft. Second, there are dangers other than a low visibility Controlled Flight into Terrain event in a box canyon. Third, I had to give the same high priority to the weather forecast on clear days as I did on cloudy ones.
Just as my box canyon encounter exposed lapses in my mental flight preparation, this report from NASA’s Aviation Safety Reporting System sheds light on a near calamity for a Cessna 210 pilot.
He was tasked to conduct an Initial Operating Experience flight with another company pilot already qualified in Cessna 210s.
The pilot wrote, “In this instance, I regarded the IOE as just a formality wherein I simply rode along with a pilot who had more time in the aircraft than I did.”
With marginal VFR conditions forecast for their route and time of flight, the IOE pilot suggested taking an IFR-certified company plane instead of the one they had been assigned, a VFR-only equipped model. The flying pilot expressed confidence that the flight would end before IMC conditions might prevail, so the IOE pilot deferred to his judgment. No plane swap was made. The pilot pair departed VFR with passengers on board.
They arrived at 9,500 feet above the river landmark leading to the summit they intended to cross. There, clouds obscured the mountain tops. Below valley visibility appeared marginal. The flying pilot claimed to have a good visual on the road leading up to the summit. They decided to press on up the canyon, but only as long as visual with the road could be maintained.
Both pilots were so locked on watching the canyon walls disappear behind misty clouds that it took a passenger to point out to them the airplane’s loss of altitude — 500 feet at that point.
That’s when the flying pilot realized he had put the plane and passengers in a bad fix. He attempted a descending 180° turn, but the IOE pilot stopped the turn. He recognized an imminent Controlled Flight into Terrain catastrophe, as they were about to descend into a box canyon.
The IOE pilot instructed the flying pilot to climb instead. They circled in the canyon, maintaining visual separation from the canyon walls until they made 12,500 feet. There, the IOE pilot gave the flying pilot a heading toward a waypoint and told him to use their VFR-only GPS for course guidance.
They departed the clouds into VFR conditions, but not before collecting a significant load of rime ice.
The reporting pilot surmised that complacency had led him to slack decision making. He summed up his analysis in the NASA report by stating, “I certainly recognize that we were fortunate to survive a situation that has killed far better pilots than ourselves.”
In actuality, those pilots were trapped in a box canyon before they even took off. By betting the flight would end before the weather worsened, the two left themselves no alternatives. If both pilots had been willing to suffer the inconvenience of the bureaucratic paperwork shuffle involved in an equipment swap, the whole situation would have been avoided.
I found at least one NASA report that revealed an unusual origin of some box canyons — bureaucracy.
New York City’s Class B airspace has an Exclusion Zone along the Hudson and East Rivers. In it, VFR aircraft can fly along the Manhattan skyline without interfering with approaches and departures from busy Kennedy, LaGuardia and Newark airports.
A 700-hour private pilot with a lot of experience flying in that Exclusion Zone took issue with how he believes the procedure in the zone must be flown.
According to this pilot, the procedure advises pilots flying north in the East River corridor to stay along the east side of the river. Southbound pilots must stay on the west side. The East River ceiling is 1,500 feet. The Hudson’s ceiling is up to, but not including, 1,300 feet mean sea level.
Pilots must execute a 180° turn just above the Manhattan Bridge to stay within uncontrolled airspace and in the corridor. This pilot estimates that the width of the corridor at the turning point is about 2,500 feet. That would seem sufficient for a low-power, slow-moving, fixed-wing airplane.
He writes: “On more than one occasion I have had to compensate for strong eastern and southerly breezes during the 180° maneuver, by first crossing to the west side of the river and then turning in a clockwise direction into the prevailing wind, returning to the west side flying in the southerly direction rather than turning counterclockwise, as one might normally. I learned to be aware of the prevailing winds after having to abort a counterclockwise turn to the opposite side when winds reduced the effective width of the river corridor and the safe execution of the maneuver seemed in doubt.”
Here’s the thing: Neither the New York Class B Airspace Hudson River and East River Exclusion training material provided by FAAsafety.gov nor the Special Flight Rules Area Guide specifically mandate or prohibit northbound flight along the East River west bank and vice versa. In fact, it is only along the Hudson River Exclusion Zone where instructions are applied.
On the Skyline Route chart, the wording is “Northbound aircraft…expect to fly along the east bank of the Hudson River…. Southbound aircraft…expect to fly along the west bank of the Hudson River.”
On the New York Special Flight Rules Area chart, the text is more direct, “…thence north along the east bank of the Hudson…” and “…thence south along the west bank of the Hudson.”
Am I the only one who sees a bureaucratic box canyon?
The bottom line is a box canyon can be physical, mental or governmental. Be wary.