Can Two Tables Have The Same Primary Key ?

I have been given a project to complete where ... two tables "Flights" and "ScheduledFlights" have a column called "FlightNo" . In both these tables it is mentioned that "FlightNo" is primary key ?
Is this possible ? i am not talking about foreign key here....

Here is the script that i have created..

create table flights
(
FlightNo char(5) constraint FlightNo primary key clustered not null,
DepTime char(5) not null,
ArrTime char(5) not null,
AircraftTypeID char(4) references Aircraft(AircraftTypeID) not null,
SectorID Char(5) references Sector(SectorID) not null
)

create table ScheduledFlights
(
FlightNo char(5) constraint FlightNo2 primary key clustered not null,
FlightDate datetime not null,
FirstClassSeatsAvailable int not null,
BusinessClassSeatsAvailable int not null,
EconomyClassSeatsAvailable int not null
)

Now the problem is with FlightNo attribute .. ? Can two Tables have the same primary key ?
(FlightNo2 is given as a temporary solution)