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[Spring Break] Friday Mar 4 travel
Monitoring remnant moisture in SEA, winds in SFO
Welcome to any new readers—we're grateful that you're here! We're building deep learning algorithms to democratize flight delay predictions; until we launch, we're eager to synthesize things manually in our outlooks. These feature several recurring themes that we recognize may be unfamiliar or intimidating, so we’ve written explainers that tackle airport arrival rates, queuing delays in the airspace and different tools to distribute those delays. If there’s a topic or mechanism you’d like to see unpacked, please let us know (same goes for special travel occasions).
We’re kicking off our Spring Break coverage with a focus on this Friday, the 4th. Hopper reports March domestic fares rose 21% year-over-year, which is impressive given that seats are up 33% (per OAG). Demand must be fairly robust for the market to have digested a healthy capacity increase with pricing intact. Spring Break travel should be spooling up this weekend before presumably peaking over the third week of March. But we’re getting ahead of ourselves—let’s stay focused on how travelers figure to get on this Friday. We’re predicting between 2.17-2.28 million travelers will be screened by the TSA; though we think there’s only a 1 in 25 chance to set a pandemic record1 for checkpoint numbers, at the higher end of our range, it’d be the third busiest day.
East Coast airports seem to garner the majority of our attention in these outlooks, so it’s a nice change of pace to write about some West Coast airports. Our backdrop will be a low pressure system moving southward from the Pacific Northwest, bringing increasingly unsettled weather to California and the Great Basin.
Despite the aforementioned low pressure system—and associated atmospheric river—having moved south of the area, SEA won’t exactly dry out tomorrow. Patchy fog will develop overnight ahead of a second system expected to pass to the west. This second system will help to keep clouds in the forecast, though any light rain should be confined to the coast. We think 40 is a serviceable arrival rate floor, with a 1 in 12 chance for lower rates and nearly 1 in 6 for equal rates. (We also want to disclose that we’ve switched the measure of historical arrival rate we’re using—from capacity to efficiency—which should remove an optimistic bias that may have previously existed.) We’ll need to keep an eye on the 10 a.m. hour, when 44 flights are scheduled2 to arrive. We’ve modeled a 40 arrival rate and resulting first-tier ground stop that produces average delays of 23 minutes3 for captured flights. There’s also 44 arrivals scheduled for the 8 p.m. hour, however conditions are forecast to improve as the day goes on.
San Francisco (SFO)
While a much-needed round of rain showers is still anticipated, the trend has been less wet. The bigger story for SFO figures to be the wind, with a wind advisory having been hoisted for the San Francisco Peninsula Pacific coast. Importantly, the San Francisco Bay coast—including SFO—is not (yet) covered by the advisory, as winds are expected to diminish somewhat as you head inland. We’ll need to watch not just the strength, but the direction, as a westerly component is forecast to gain influence (over northerly) along the Bay shoreline. We’ll follow on to this post with tweets as TAFs are updated; for the meantime, we’ll use the national blend of models (NBM), which keeps direction between 280-290° and speeds below 25 knots. With that said, we like 35-36 for an arrival rate and put chances at nearly 3 in 5 (it’s also a good floor, with about 1 in 10 chance for lower rates).
There’s also a demand narrative worth highlighting at SFO: good for travelers tomorrow, though sad as far as the industry is concerned. Of the FAA’s Core 30 airports, SFO ranks 29th in terms of their flight schedule recovery4. While the market implications may be worrisome, in the near term it means just one potential demand overage of note exists. 45 flights are scheduled to arrive in the 9 p.m. hour, though winds should be on the backside of their peak by then. Again, we’d bet the FAA reaches for a first-tier ground stop and we’ve modeled average delays of 31 minutes (lingering into the 10 p.m. hour) for first-tier arrivals, assuming a 35 arrival rate. Though the noon and 3 p.m. hours don’t don’t exceed 33 scheduled arrivals across 60 minutes, there is some backloading of demand in both hours—a 35 or 36 rate during these periods would produce some delays via miles-in-trail/metering, though delays should average just 10 minutes and be short-lived.
Los Angeles (LAX)
The weather setup at LAX is similar to SFO, with rain amounts trending down and fairly strong winds expected in the wake of the low. Notably, a slight chance for thunder exists for LAX (unlike SFO) and it appears there’s less question as to the direction of the wind (left of 280° in LAX’s case). As the low exits the area Friday afternoon, showers should taper off fairly quickly. With two exceptions, LAX should be a relatively simple case: we’d put the arrival rate floor at 66 (1 in 15 chance for lower rates) and scheduled demand peaks well underneath that at 45. The first qualification is a wind shift forecast for around 8 a.m. that could prompt a configuration change—and waste a few landing slots while they turn the airport around. If the forecast verifies and the wind shift occurs around 8 a.m., demand is relatively low at 28 arrivals and the configuration change should be of little matter; if the wind shift is late by an hour, demand in the 9 a.m. hour is 44 and some [still-limited] airborne holding is more probable. The second thing to watch for would be lightning coverage—all it takes is one strike for baggage handlers and fuelers (among other workgroups) to be pulled off the ramp, thus halting aircraft turnarounds.
Salt Lake City (SLC)
As the low pressure system dives inland from Southern California, a plume of moisture will be drawn northward, reaching the southwestern mountains of Salt Lake City by early Friday morning. Precipitation chances increase into late Friday, though cooler air doesn’t look to arrive until late Friday night. Resultantly, probabilities for snow (per short range ensemble guidance) remain under 10% through 11 p.m, helping to eliminate deicing and snow removal delays from the equation. As such, we’ll establish our arrival rate floor at 60, with about a 1 in 8 chance for equal or lower rates. Provided unscheduled demand is not extraordinary—even by SLC’s high standards—demand, whose scheduled peak is 34, should be accommodated without delay.
Odds and Ends
Though not hub airports, we do want to mention Las Vegas (LAS) and San Diego (SAN), as they’re both destinations that figure to receive more than their fair share of Spring Break traffic. For LAS, moisture will be largely squeezed out by the Sierras as the low pressure system moves inland. Though unscheduled demand caveats especially apply here, our low end arrival rate of 44 (1 in 4 chance for lower rates) should accommodate scheduled demand (which peaks at 33) without delay.
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Unsurprisingly, SAN’s forecast is not too different from LAX, with showers, a chance of thunderstorms (though more concentrated pre-dawn) and gusty winds (albeit more southerly). Here, a 24 arrival rate is a pretty safe bet: about 19 in 20, with the alternative being a 22 rate. Scheduled arrival demand peaks at 23 in the 8 p.m. hour, though the next tallest peak is just 18. Unscheduled and scheduled arrival demand could conceivably coalesce to create a demand overage in the 8 p.m. hour, though the lack of information as to what unscheduled demand will look like makes it difficult to speculate on delay shape and intensity.
No weather waivers are out for this Pacific system, though we’ll take the opportunity to remind readers that airlines have meaningfully improved general rebooking flexibility by eliminating change fees for most tickets (though a fare difference may still apply). We’ve linked to the same-day change policies for Delta (who operates a SEA hub) and United (SFO). If you have a layover in SEA around 11 a.m. or SFO around 10 p.m. that can’t absorb a delay of 25-30 minutes, we’d at least check out alternative routings if we were holding the literary.
Our thoughts are with the people of Ukraine, especially the Kyiv-based designer we partnered with this past fall.
We were a bit surprised that airlines’ mileage donation programs haven’t kicked into gear yet, but Miles4Migrants indicates NGO’s haven’t begun to submit requests for displaced Ukrainians. In the interim, they recommend donating to their partners IRC, HIAS, and UNHCR. Alternatively, you can donate to Airbnb’s efforts to house Ukrainian refugees if you wish to stay in the travel sector.
If your experience reading this post is anything like ours writing it, you’ll check Jon Ostrower’s Open Source Intelligence list on Twitter between every sentence. Given the tone on social media, we’ll be doing less self-promotion for the time being—with that said, we’d be particularly appreciative of anybody who shares this bit of writing.
Currently owned by the Sunday after Thanksgiving 2021 (2.45 million).
Cargo airlines as well as private jets are not included in scheduled demand and only become apparent when they file a flight plan (generally day-of). This unforeseen demand introduces the risk that delay probabilities/intensities are under-forecast. Unscheduled demand added 9.1% to scheduled demand for Core 30 airports year-to-date. For the airports we’ll consider today, SFO (9.2%), LAX (11.1%, though likely inflated by Super Bowl), SAN (16.9%), LAS (24.1%) and SLC (34.9%) are above average.
While our modeling is aimed at tackling arrival delays, there's a strong correlation to departure delays (albeit with some lag and/or possible alleviation). Consider a scheduled "turn" at an airport: the inbound flight is scheduled to arrive at 2:19 p.m. and departs at 3:30 p.m. (71 minutes of turnaround time). Let's say the inbound is delayed by 40 minutes and instead arrives at 2:59 p.m. We'll further assume that the airline doesn't need the full 71 scheduled minutes to turn the aircraft and can accomplish the turn in 45 minutes if they hustle - the departure will push back from the gate at 3:44 p.m. (delayed by 14 minutes). In this example, a 40 minute arrival delay in the 2 p.m. hour is partially passed through to a departure in the 3 p.m. hour. Had the turnaround been scheduled at 45 minutes instead (i.e. no turnaround buffer), the lag between arrival and departure delay would still exist, however the delay would be fully passed through.
Additionally, our efforts are aimed at diagnosing air traffic delays (i.e. those that result from an imbalance between capacity and demand). Though not the focus of our efforts (yet), delays owing to aircraft servicing, airline staffing, network effects, etc. are always lurking.
Core 30 airports are ATL, BOS, BWI, CLT, DCA, DEN, DFW, DTW, EWR, FLL, HNL, IAD, IAH, JFK, LAS, LAX, LGA, MCO, MDW, MEM, MIA, MSP, ORD, PHL, PHX, SAN, SEA, SFO, SLC, TPA.
March 2022 SFO frequencies are off 31% from March 2019 levels, behind only PHL (33%); average is 16% down year-over-three.