United Airlines Flight Search

Purpose

Given an origin airport, destination airport, depart date (and optionally a return date), trip type (one-way or round-trip), and a passenger count, return the list of available United Airlines flights for those parameters — each flight's departure / arrival times, duration, stop count, flight number(s), cabin class, fare brand, and price. Read-only — never click "Select", "Continue", or any seat / fare / book button. Stop at the results page (/en/us/fsr/choose-flights).

When to Use

• "What are the cheapest non-stops SFO → JFK on July 15?"
• "Compare one-way vs round-trip pricing on LAX → ORD next Friday."
• Daily price-watch across a fixed origin/destination/date.
• Any flow that needs UA's published fares + schedules without committing to a booking.
• Do not use this skill for award-mile / MileagePlus searches — those live on a different surface (/ual/en/us/flight-search/book-a-flight/results) and have a different fare model.

Workflow

The United flight-search UI is a JavaScript SPA. The cleanest path is to navigate directly to the search-results deep-link URL (/en/us/fsr/choose-flights?f=...&t=...&d=...&r=...&tt=...) instead of filling the homepage's typeahead form — this skips airport autocomplete, date-picker, and trip-type radio entirely, and avoids the typeahead-timing bugs that the form path is prone to. The page is still client-side rendered, so a real browser session is required to harvest the flight cards; the URL is just a shortcut into the right page state.

A residential-proxy + verified (Verified) Browserbase session is mandatory — the site is fronted by Akamai and a bare datacenter IP gets cookie / _abck challenges before any results render.

1. Verified + residential-proxy session

SID=$(browse cloud sessions create --keep-alive --verified --proxies | jq -r .id)
export BROWSE_SESSION="$SID"

Both --verified (Verified browsers) and --proxies (residential proxy pool) are required. Confirmed via browse cloud fetch evidence: _abck and bm_* Akamai cookies are set on every response, and a bare-IP session gets a challenge page in place of the SPA shell.

2. Construct the deep-link URL

https://www.united.com/en/us/fsr/choose-flights
  ?f={ORIGIN_IATA}
  &t={DEST_IATA}
  &d={DEPART_YYYY-MM-DD}
  &r={RETURN_YYYY-MM-DD}          # omit for one-way
  &tt={1|0|2}                      # 1=round-trip, 0=one-way, 2=multi-city
  &sc=7                            # search-class — keep 7 for cash fares
  &px={PASSENGER_COUNT}            # integer, 1–9
  &taxng=1                         # show all-in (taxes included) pricing
  &clm=7                           # cabin: 7=Economy, 6=Premium Economy, 4=Business, 3=First
  &st=bestmatches                  # bestmatches | priceasc | departtime | arrivetime | duration
  &newDateOverride=true            # use new date logic — safer on cross-month dates

Examples (both validated as 200 OK via browse cloud fetch --proxies against the production host):

# Round-trip SFO → JFK, depart 2026-07-15, return 2026-07-22, 1 adult, Economy
https://www.united.com/en/us/fsr/choose-flights?f=SFO&t=JFK&d=2026-07-15&r=2026-07-22&tt=1&sc=7&px=1&taxng=1&clm=7&st=bestmatches

# One-way SFO → JFK, depart 2026-07-15, 1 adult, Economy
https://www.united.com/en/us/fsr/choose-flights?f=SFO&t=JFK&d=2026-07-15&tt=0&sc=7&px=1&taxng=1&clm=7&st=bestmatches

The URL accepts the airport as IATA code only (SFO, JFK, LAX, ORD, EWR, LHR, ...). City names, station IDs, or anything else gets coerced to a "no flights" state. If the caller hands you a city name, resolve it to an IATA code first (United's airport-lookup API at /api/airports/lookup/search returns 404 — not a usable surface — so resolve client-side from a static IATA table).

3. Open the URL and wait for cards to render

browse open "$URL" --remote
browse wait load
browse wait timeout 4000          # SPA hydrates results ~2–4s after `load`
browse snapshot

The first paint of the results grid is client-side — browse wait load alone is not sufficient; flight cards aren't in the DOM until the searchFsr XHR resolves. Empirically 3–4 seconds covers the long tail. If the snapshot returns 0 flight-card refs, sleep another 2s and retry once before declaring failure.

4. Branch on what the snapshot shows

5. Extract flight cards

Each card on the results grid exposes:

• Depart time — first time string in the card (08:30, in the rendered local airport time).
• Arrive time — second time string.
• Duration — explicit text like 5h 35m (or 5h 35m +1d for next-day arrivals).
• Stop count — text like Nonstop, 1 stop, 2 stops. Parse to an integer.
• Flight numbers — text like UA 232 (or UA 232, UA 7411 on multi-leg). Capture the full list.
• Cabin / fare options — typically Basic Economy / Economy / Premium Plus / Business / First, with one price each. Capture the lowest-cabin price unless the caller specified a higher cabin via clm.
• Price — USD number, sometimes shown as $348.20* (the * indicates a Saver/award-mix fare — strip when emitting clean numbers, surface as flags: ["saver"]).

For round-trip, the page renders outbound cards first; after the user selects an outbound, return cards render on a follow-up screen. To stay read-only, extract only the outbound cards and emit them as results. If the caller wants return-leg pricing too, run a second one-way search with f / t swapped and d=<return date>.

6. Release the session

browse cloud sessions update "$SID" --status REQUEST_RELEASE

Form-fill fallback (only if the deep-link URL stops working)

If United changes the FSR URL schema and the deep-link returns the homepage redirect or a date-picker overlay on every load, fall back to driving the homepage form:

1. browse open https://www.united.com/ --remote
2. Wait for the "Book travel" widget to mount (browse wait timeout 3000).
3. Click the trip-type radio: One-way or Round-trip (default is Round-trip).
4. Click the From field, type the IATA code (SFO), wait 2000ms for the typeahead dropdown, then click the first option matching the code. Do not use browse fill — it auto-presses Enter, which submits the field before the typeahead surfaces. Use click → type → wait timeout 2000 → click <suggestion-ref>.
5. Repeat step 4 for the To field.
6. Click the Depart date field; the date-picker overlay opens. Navigate to the target month with the > button, click the target day. For round-trip, the picker stays open; navigate + click the return day. Confirm with the picker's Done / Apply button.
7. (Optional) Update passenger count + cabin via the Travelers / Cabin dropdown.
8. Click Find flights. Page navigates to /en/us/fsr/choose-flights?... with the params URL-encoded. From here continue at step 3 of the deep-link path.

Form-fill is ~3× slower than the deep-link path and adds two failure modes (typeahead-race, date-picker-month-overshoot), so use only when the deep-link is confirmed broken.

Site-Specific Gotchas

• READ-ONLY. Never click Select, Continue, Book, Add to cart, or a fare-option price button — any of these starts the booking funnel and may hold inventory.
• Akamai is on every path. Both / and /en/us/fsr/choose-flights?... set _abck, bm_ss, bm_s, bm_mi, and akacd_NS_AB cookies on the first response. A datacenter-IP session without Verified will be challenged on the second navigation. --verified --proxies is the minimum viable session config.
• Pure SPA — no embedded results state. browse cloud fetch of the deep-link returns the React shell HTML (~75 KB) with zero flight data embedded. There is no scraping shortcut that skips the browser; you must let the page hydrate. Verified by grepping the fetched body for searchContext|fareFamily|cabinClass|currentSearchCriteria — zero matches.
• /api/flight/recentSearch returns 405 Method Not Allowed to GET. The endpoint exists internally but only accepts authenticated POSTs from the SPA's signed-session context. Don't waste time trying to reverse-engineer United's internal searchFsr JSON endpoint — it's behind anti-tamper headers + session cookies that aren't reproducible from an out-of-band fetch. Drive the browser instead.
• /api/airports/lookup/search returns 404. The airport-typeahead endpoint is not at the obvious path. If you need IATA-code lookup, use a static IATA table (carry one in the skill harness) rather than trying to hit a United-side resolver.
• Date format must be YYYY-MM-DD. The URL parser accepts 2026-07-15; anything else (07/15/2026, 15-Jul-2026, ISO with timezone) silently drops back to the date-picker overlay.
• tt=1 is round-trip, tt=0 is one-way, tt=2 is multi-city. Counter-intuitive direction. tt=2 requires a different param layout (f1/t1/d1, f2/t2/d2, ...) and is out of scope for this skill.
• Cross-month / past dates → date-picker re-opens. If the date-picker overlay re-appears instead of cards rendering, the requested date was rejected. Common causes: date in the past, date > 11 months out (UA's booking window), or wrong format.
• taxng=1 is important. Without it, the listed prices are base-fare-only (no taxes/fees), which gives misleadingly low quotes. Always include it for "what does this cost?" queries.
• * on prices = Saver / mixed-cabin fare. Strip the asterisk when emitting numeric prices; surface as flags: ["saver"].
• "No flights available" is a valid success. Combinations like (very short window) + (small regional pair) + (high cabin class) frequently return an empty grid. Emit success: true, results: [], no_flights_for_dates: true — not a failure.
• The deep-link can also accept noflex=true to disable the flexible-date calendar above the grid (saves ~1s on hydration). Optional.
• Award-mile pricing is on a different URL. /ual/en/us/flight-search/book-a-flight/results is the award flow; do not confuse the two surfaces — they have different fare models, different cabin enums, and a different results DOM.
• Round-trip cards only show outbound on the first page. The return-leg grid only renders after an outbound is selected, which is a click this skill must NOT make. If both legs are needed, do two one-way searches and combine client-side.

Expected Output

{
  "success": true,
  "trip_type": "round-trip",
  "origin": "SFO",
  "destination": "JFK",
  "depart_date": "2026-07-15",
  "return_date": "2026-07-22",
  "passengers": 1,
  "cabin": "economy",
  "results_url": "https://www.united.com/en/us/fsr/choose-flights?f=SFO&t=JFK&d=2026-07-15&r=2026-07-22&tt=1&sc=7&px=1&taxng=1&clm=7&st=bestmatches",
  "results": [
    {
      "depart_time": "08:30",
      "depart_airport": "SFO",
      "arrive_time": "17:05",
      "arrive_airport": "JFK",
      "next_day_arrival": false,
      "duration": "5h 35m",
      "stops": 0,
      "flight_numbers": ["UA 232"],
      "cabin_class": "Economy",
      "fare_brand": "Basic Economy",
      "price_usd": 348.20,
      "flags": []
    },
    {
      "depart_time": "10:15",
      "depart_airport": "SFO",
      "arrive_time": "21:48",
      "arrive_airport": "JFK",
      "next_day_arrival": false,
      "duration": "8h 33m",
      "stops": 1,
      "flight_numbers": ["UA 481", "UA 1722"],
      "cabin_class": "Economy",
      "fare_brand": "Economy",
      "price_usd": 412.40,
      "flags": ["saver"]
    }
  ],
  "no_flights_for_dates": false,
  "error_reasoning": null
}

Distinct outcome shapes:

// Success — flights returned (canonical case)
{ "success": true, "results": [ /* ≥1 flight */ ], "no_flights_for_dates": false, "error_reasoning": null, ... }

// Success — no flights for the requested dates / cabin / route
{ "success": true, "results": [], "no_flights_for_dates": true, "error_reasoning": null, ... }

// Failure — Akamai challenge (session burned, retry with a fresh Verified session)
{ "success": false, "results": [], "error_reasoning": "akamai_challenge", ... }

// Failure — invalid input (unrecognized IATA, malformed date, past date)
{ "success": false, "results": [], "error_reasoning": "invalid_input: <field>=<value>", ... }

// Failure — site error banner ("We're unable to process your request")
{ "success": false, "results": [], "error_reasoning": "site_error_banner", ... }