United Flight DL400 Deals & Information (2025/2026)

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United Flight 400 Route Deals From $80

The cheapest prices found with in the last 7 days for return flights were $119 and $80 for one-way flights to O'Hare Intl. for the period specified. Prices and availability are subject to change. Additional terms apply.

Thu, Sep 4 - Sun, Sep 7
ATL
Hartsfield-Jackson Atlanta Intl.
ORD
O'Hare Intl.
$119 Roundtrip, found 1 hour ago
$119
Roundtrip
found 1 hour ago
Select United flight, departing Thu, Sep 4 from Hartsfield-Jackson Atlanta Intl. to O'Hare Intl., returning Sun, Sep 7, priced at $119 found 1 hour ago
Fri, Aug 1 - Tue, Aug 5
ATL
Hartsfield-Jackson Atlanta Intl.
ORD
O'Hare Intl.
$123 Roundtrip, found 12 hours ago
$123
Roundtrip
found 12 hours ago
Select United flight, departing Fri, Aug 1 from Hartsfield-Jackson Atlanta Intl. to O'Hare Intl., returning Tue, Aug 5, priced at $123 found 12 hours ago
Wed, Sep 3 - Sat, Sep 6
ATL
Hartsfield-Jackson Atlanta Intl.
ORD
O'Hare Intl.
$137 Roundtrip, found 13 hours ago
$137
Roundtrip
found 13 hours ago
Select United flight, departing Wed, Sep 3 from Hartsfield-Jackson Atlanta Intl. to O'Hare Intl., returning Sat, Sep 6, priced at $137 found 13 hours ago

Frequently asked questions

What route does flight number UA400 take?
UA400 operates from Dulles Intl. Airport to Raleigh--Durham Airport and is a direct flight. This trip takes 1 hour and 11 minutes.
What kind of plane is on flight number UA400?
The route for flight number UA400 is generally Dulles Intl. Airport to RDU, and the Boeing 737-800 is the aircraft model you'll probably be flying with.
If I am not able to travel due to COVID-19, can I change my flight to a later date?
For more info about changing your UA400 flight with Travelocity, please visit our Customer Service Portal.