5/25/2015 Operations Research Group Continental Airlines Bridging Schedule Changes When Bookings...

04/18/23 Operations Research Group

ContinentalAirlines

Bridging Schedule Changes When Bookings Exist

Judy Pastor

Continental Airlines

AGIFORS YM 2002 - Berlin


ContinentalAirlines On September 1, 2001

• Airline industry changed dramatically

• Continental reduced schedule by 20%

• But bookings existed on full schedule for the next 330 days

• Situation magnified an existing problem


ContinentalAirlines CRSs and Schedule Change

• Continental’s CRS Reaccom process– Input is flight (old schedule) to flight (new schedule)

mapping for a future date range– All passengers from flight in old schedule are moved

to specific flight in new schedule• No attention given to connecting segments• AU levels for new flights are not respected• Human intervention needed to correct


ContinentalAirlines Result of Current Process

• Costly in terms of

– Customer Satisfaction• Self-imposed misconnections for connecting pax• Confusion at airport

– Recovery• “Hot” flights DB Costs• Reaccom at airports

– Revenue opportunity• LY pax moved to flights with HY opportunity


ContinentalAirlines Schedule Change Reaccom

• OR group saw opportunity to combine rich information contained in PNR Data Warehouse and Mathematical Programming

• Solution– Build new flight network and flow passengers from

existing schedule onto it– Large problem that looked intractable at first– Analysis led to ways to reduce it


ContinentalAirlines Multi-Step Process

• Current algorithm focuses on one day of reaccom but recognizes prior and subsequent days– Due to itineraries that span days– So that reaccom can be done in one flight/day

markets


ContinentalAirlines Schedule Match

• Get proposed schedule from Schedule Administration

• Retrieve current schedule

• For each date of interest, match proposed schedule to current

• Each flight in new schedule is either a Match or a Change


ContinentalAirlines Types of Flight Changes

• No Match– Caused by a change in frequency– Flight in old schedule has no match in new

• Retime– Old flight matches in new schedule but with timing

change• Into Hub – arrival time > 10 min later• Out of Hub – departure time > 10 minutes earlier• Any time change more than 30 minutes

• Match with Equipment Downgauge– If current bookings > new capacity


ContinentalAirlines Schedule Match Example

OD: RDUIAH DeptDate: 20707 DOW: 7 Old Schedule Num Flights: 3FltNum 151 Dept 635 Arrl 829 Bkd 34 AU 110 CAP 104 Status: OKFltNum 1751 Dept 1453 Arrl 1650 Bkd 77 AU 110 CAP 104 Status: No MatchFltNum 551 Dept 1740 Arrl 1935 Bkd 36 AU 135 CAP 124 Status: OK New Schedule Num Flights: 2FltNum 151 Dept 635 Arrl 829 735 CAP 104 Status: OKFltNum 551 Dept 1740 Arrl 1935 733 CAP 124 Status: OK Old Total Cap: 332New Total Cap: 228 Bkd: 147 Re-Timed: 0 No Match: 77 Downgauge: 0


ContinentalAirlines Effected PNRS

• Next step is to retrieve PNRs for flights that are classified as a Change– Get all active legs in PNR for the focus date, the day

before and the day after• Create new schedule with recomputed current

booked, capacity and AU– Matched flights get booked from old schedule minus

any connecting legs from PNRs of changed flights– Unmatched flights will have current booked of zero


ContinentalAirlines New OD Paths

• Enumerate feasible O and D paths for new schedule for PNRS from changed flights– Non stops– One stops (limit to total trip time < nonstop + 4

hours if nonstop exists)– Two stops (if less than 6 paths)– Three stops (if nothing yet)– Alternate stations can be specified @ penalty


ContinentalAirlines Alternate Paths for RDUGYE 20020707

151 RDUIAH 20020706 620 814 888 IAHPTY 1445 1846 887 PTYGYE 2250 2445 244 RDUEWR 20020706 1400 1529 887 EWRPTY 1750 2200 887 PTYGYE 2250 24454146 RDUEWR 20020706 1150 1316 887 EWRPTY 1750 2200 887 PTYGYE 2250 2445 144 RDUEWR 20020707 935 1100 887 EWRPTY 1750 2200 887 PTYGYE 2250 2445 244 RDUEWR 20020707 1400 1529 887 EWRPTY 1750 2200 887 PTYGYE 2250 24454146 RDUEWR 20020707 1150 1316 887 EWRPTY 1750 2200 887 PTYGYE 2250 2445 151 RDUIAH 20020707 635 829 888 IAHPTY 1445 1846 887 PTYGYE 2250 2445 151 RDUIAH 20020708 640 834 888 IAHPTY 1445 1846 887 PTYGYE 2250 2445 351 RDUIAH 20020708 1156 1350 818 IAHUIO 1720 2224 818 UIOGYE 2310 2359 351 RDUIAH 20020708 1156 1350 888 IAHPTY 1445 1846 887 PTYGYE 2250 2445 244 RDUEWR 20020708 1400 1529 887 EWRPTY 1750 2200 887 PTYGYE 2250 2445 528 RDUEWR 20020708 945 1111 887 EWRPTY 1750 2200 887 PTYGYE 2250 24454146 RDUEWR 20020708 1150 1316 887 EWRPTY 1750 2200 887 PTYGYE 2250 2445


ContinentalAirlines Demand

• Aggregate demand by Path O and D and class of service

• Flow aggregated demands on new schedule network via the enumerated paths to minimize penalties– Change from original departure, arrival, trip time– Number of flights in itinerary– Multiplier for class of service (more penalty for YH)– Use of alternate stations for origin or destination


ContinentalAirlines Flight Capacity Constraints

• Capacity constraints on flights in new schedule

– RHS for matched flights = new cap – recomputed current booked

– RHS for changed flights = new cap

• Solve LP

• Solution will flow old path O and Ds by class of service on new schedule


ContinentalAirlines Solution Example

OLD FLT 1751 RDUIAH Dept 1453 Arrl 1650 - NO MATCH IN NEW SCHEDULE Path RDUGYE NumPax 76 COS B #Flts 3 PathDate 20020707

Dept 1453 Arrl 2359Penalty 43.4

FLT 244 ddate 20020707 od RDUEWR dept 1400 arrl 1529 FLT 887 ddate 20020707 od EWRPTY dept 1750 arrl 2200 FLT 887 ddate 20020707 od PTYGYE dept 2250 arrl 2445


ContinentalAirlines Assign Existing PNRs

• Assign PNRs to new paths via bin packing algorithm– blocks of space assigned by O and D– individual PNRs must now fit into blocks as closely

as possible– may need to amend “optimal” solution to fit PNRs

exactly


ContinentalAirlines PNR Assignment

OLD FLT 1751 RDUIAH Dept 1453 Arrl 1650 - NO MATCH IN NEW SCHEDULEPath RDUGYE NumPax 76 COS B #Flts 3 PathDate 20020707 Dept 1453 Arrl 2359 Penalty 43.4 FLT 244 ddate 20020707 od RDUEWR dept 1400 arrl 1529 FLT 887 ddate 20020707 od EWRPTY dept 1750 arrl 2200 FLT 887 ddate 20020707 od PTYGYE dept 2250 arrl 2445 PNRsrcrdloc UFSGF2 numpax 6rcrdloc UFRKEK numpax 70


ContinentalAirlines Other Uses

• Integrate with Demand Driven Dispatch to swap aircraft to allow for better re-accommodation in very tight situations

• Proactive pre-flight re-accom to create more space on flights where too many bookings have already been taken

• Heads Up Tool for Scheduling to determine where extra sections may be needed


ContinentalAirlines Questions?

5/25/2015 Operations Research Group Continental Airlines Bridging Schedule Changes When Bookings...

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