mysql - Error (1005) when trying to create foreign key -

i'm trying create basic foreign constraint, i'm getting syntax error. #1005 - can't create table 'my_database'.'#sql-334f_952bc' (errno: 150 "foreign key constraint incorrectly formed")

i first create tables , use 'alter table' method create foreign constraint.

creating tables:

create table `tbl_flights` (   `flight_id`      int(11)       not null auto_increment   `aircraft_id`    int(11)       not null   `date`           date          not null   `auth_by`        varchar(255)  not null   `auth_duration`  time          not null   primary key (`flight_id`) ) ;  create table `tbl_aircraft` (   `aircraft_id`    int(11) not null auto_increment   `registration`   char(6) not null   `insurance`      date    not null   `awrc`           date    not null   primary key (`aircraft_id`)  ) ; 

creating foreign key/constraint:

alter table `tbl_aircraft`  add constraint  `fk_aircraft_id` foreign key ( `aircraft_id` )  references `my_database`.`tbl_flights` ( `aircraft_id` )  on delete restrict on update cascade ; 

if identify issue here appreciate it.

base in error message missed ; @ end of statement

create table `tbl_flights` (   `flight_id`      int(11)       not null auto_increment   `aircraft_id`    int(11)       not null   `date`           date          not null   `auth_by`        varchar(255)  not null   `auth_duration`  time          not null   primary key (`flight_id`) ) ; /* add */  create table `tbl_aircraft` (   `aircraft_id`    int(11) not null auto_increment   `registration`   char(6) not null   `insurance`      date    not null   `awrc`           date    not null   primary key (`aircraft_id`)  ) ; /* add this*/ 

could have inverted tables

 alter table `tbl_flights`   add constraint  `fk_aircraft_id` foreign key ( `aircraft_id` )   references `my_database`.`tbl_aircraft` ( `aircraft_id` )   on delete restrict on update cascade ; 

or must add foreign column in table tbl_aircraft