Flight Deals from San Francisco to Bucharest from $471

Airlines and weekly frequencies are compiled from our flight-schedule database, which combines published airline timetables, U.S. government schedule data from the Bureau of Transportation Statistics (BTS), and observed flight operations from the EUROCONTROL/OpenSky Open Performance Data Initiative (OPDI). We count each operating carrier's scheduled weekly departures and the days it flies; where there is no nonstop service, connecting carriers are identified by linking scheduled nonstop segments through common hub airports. Where a median fare is shown for a carrier, it reflects the real fares Priceline users found on this route in the last 72 hours. Carrier service, flight times and distances for this route come from our flight-schedule database, which draws on published airline timetables, U.S. government schedule data, and observed operations from the EUROCONTROL/OpenSky Open Performance Data Initiative (OPDI). We report the days of the week and the departure times each carrier operates. The typical flight time is the median scheduled block time, given both per carrier and across all carriers on the route; where a schedule does not publish an elapsed time, it is derived from the scheduled departure and arrival times converted to UTC. Outbound and return times are computed by the same method, so the difference between them is directly comparable and reflects prevailing winds rather than any change in derivation. Distance is the great-circle distance between the two specific airports named, so an actual flown track is typically 2-5% longer. Where shown, on-time departure and arrival rates and cancellation rates come from the U.S. Bureau of Transportation Statistics (BTS) Airline On-Time Performance dataset, which covers U.S. domestic routes only; where a typical fare is shown, it comes from the U.S. DOT Airline Origin and Destination Survey (DB1B), a quarterly 10% sample of tickets sold.

This 'good deal' estimate shows a representative best price for each departure date across roughly a 12-month window (about 3 months back and 9 months forward). It is built from real flight prices found by Priceline users searching this route, accumulated into a price history for each departure date. Rather than weighting all of that history equally, we apply exponential time decay so recent prices dominate — a price seen yesterday counts almost in full, one from about a month ago roughly a third, and prices from a few months back very little — giving a figure that tracks today's market instead of a stale long-run average. Clear price outliers are removed before any calculation, departure dates with no observations are filled in from nearby dates, and the resulting curve is lightly smoothed so it reads as a clean seasonal trend rather than day-to-day noise.

This booking-window guidance is built from the same real flight prices found by Priceline users searching this route, re-grouped by how many days before departure each price was seen (from the departure day out to about 180 days ahead) across the route's price history. At each booking lead time we report the 25th-percentile price — the cheaper end of what travelers were quoted, rather than the rock-bottom minimum (which can be a fluke) or the average (which is pulled up by expensive last-minute fares). The buy-or-wait advice then applies a risk premium that grows as departure approaches, since seat availability shrinks and prices become less predictable; using that adjusted curve we flag windows where waiting is likely to save a meaningful amount (at least $20 or 5%) versus windows where booking now is the better call. Isolated single-day recommendations are filtered out, so the advice only reflects a window that holds for several days in a row.

Red-eye flights are identified from scheduled local departure and arrival times in our flight-schedule database — built from published airline timetables and official schedule data, including U.S. Department of Transportation records for domestic routes — flagging services that depart late at night and arrive the following morning; for connecting itineraries the red-eye is based on the timing of the overnight long-haul leg.

Airlines and weekly frequencies are compiled from our flight-schedule database, which combines published airline timetables, U.S. government schedule data from the Bureau of Transportation Statistics (BTS), and observed flight operations from the EUROCONTROL/OpenSky Open Performance Data Initiative (OPDI). We count each operating carrier's scheduled weekly departures and the days it flies; where there is no nonstop service, connecting carriers are identified by linking scheduled nonstop segments through common hub airports. Where a median fare is shown for a carrier, it reflects the real fares Priceline users found on this route in the last 72 hours.

Aircraft types are taken from the equipment each operating carrier schedules on this route, drawn from published airline timetables and airline equipment schedules in our flight-schedule database. They describe typical scheduled aircraft and can vary with seasonal or day-of-week assignments and last-minute equipment swaps.