Ebonitus exclaims "What the...", as he looks around at the carnage, then dashes over to Dork and putting the rings together casts Warding Bond on the metal maiden.

for his bonus action (if he gets one), he will check for a pulse in the nearest collapsed crewman.

Ebonitus looks at the ballista in the bow, and quickly realises it can't be swung around to target the dragon which is approaching from the [Starboard stern quarter = 1 & 2, Directly astern = 3 & 4, Port stern quarter = 5 & 6] {5} - at least not without severely damaging the webbing attaching the canopy to the airship - rushes over to assist D.O.R.K. 

(OOC - you can't do a check as a bonus action)

The cultist in the bow with Ebonitus drops to his knees and starts kow-towing as the dragon flies past.

Initiative: Devin, Mullo, Illezenya, Aze the Magnificent, Ebonitus, D.O.R.K. 

Devin watches as the green dragon banks around for another pass.  He looks to his companions who are better fighters than he and casts Bless (at lvl 2) on each of them.

"I've got a bad feeling about this.  Why can't dragons leave us alone?" as he grips his shield tighter.

(Soothing Twilight - 9 rounds left. My companions within 30' and I gain another 9 temporary hps.)

"Stay close and feel the soothing twilight give you comfort and calm your mind," Ilezenya calls to his companions as his spiritual weapon continues to attack the dragon. (Bonus action - Attack: 22 Force Damage: 7)
The Dusk Warden also directs a streak of light towards the dragon as it approaches. (Action - casting Guiding Bolt at 3rd level.  Attack: 15 Radiant Damage: 27. On a hit, the next attack roll made against the dragon before the end of Ilezenya's next turn has advantage, thanks to the mystical dim light glittering on it.)

Would Mullo know the comparative speeds of a dragon its size and Haetone? Would she know if there was a chance of outrunning it or if the dragon would overtake them in a short time?

Mullo turns Haetone in an attempt to get within 30 feet of the dragon.

I'm sure that over time Mullo has probably encouraged Haetone to race other flying creatures. She would know that at maximum speed (without dashing), they probably have about a bit over a mile an hour advantage (10' per round) on the dragon.

Yes Mullo and Haetone can get within 30 feet of the dragon which seems to be lining up for the stern of the airship anyway.

Aze the Magnificent lands on the deck of the airship spying the dead bodies of the three cultists lying around says "I'm not going to bother using my most potent weapon on you as I need some living slaves" as he bites (1-2 = Devin, 3-4 = D.O.R.K.,  5-6 = Ebonitus, or 7-8 = Illezenya) {1} and then knowing it better not split his attacks slashes at his chosen victim.

On Ebonitus
Bite = Attack: 16 Damage: 8 plus 7
First claw = Attack: 22 Damage: 13
Second claw = Attack: 11 Damage: 10

for a total of 38 points of slashing damage.

Despite his deep lacerations Ebonitus is still standing. 

Aze looks around and says "if you wish to surrender I'll accept your obeisance now!"

Ebonitus you're up

(Don't forget the two rounds of temporary HP you've gained =)

Ebonitus looks at the dragon and says "Surrender,! to you! Ha! Today is not that day you puny soft green lizard! It's only a flesh wound" And while he says this he raises his hand and calls upon the Earth mother, then pointing at the dragon a large hammer appears above the dragon and strikes hard upon his head.

In combat, Ebonitus maneuvers (not disengaging) himself towards the bow of the ship to separate himself from his companions to make it harder for the dragon to capture all of us in the one breath.

(Assuming advantage from Ilezenya's Guiding bolt.)

Bonus action: Spiritual Weapon Attack: 24 Damage: 5 Force damage.

Forgot to add the Bless to the attack roll: 1 

As a clarification, by maneuver without disengaging, I am remaining in combat with the dragon, just subtly directing toward the bow.

For his action Ebonitus will caast Sacred Flame upon the dragon's head and the dragon must save (Dex DC:15) or take 13 radiant damage.

The light of D.O.R.K's eyes flicker to their more blue-hued confusion at Ebonitus antics, but any questions are not forthcoming in the heat of the moment. Rather in the wake of it, she frees a hand to utter a soft prayer while tracing the symbol on her forehead, leaving the symbol burning brightly orange and radiating a gentle field of light across much of the ship. Those within previously accosted by poison would even feel the breathe easier, and the linger sting start to dissipate. Then at the risk of being knocked over board, if able to get to dragon's sides, than she would do so without leaving the reach of the dragon. Even if that meant coming perilously close to the edges in the process.

"This operative is in agreement. Remove yourself from this ship and cease hostilities. We wish only continue our divinely ordained pilgrimage to end the ongoing giant threat. Persist, and you shall be removed by further force." Her eyes turn fully into their combat mode tones. "You have been warned."

Action: Cast (4th level)Celestial's Purity (which should affect all the party within 30ft of D.O.R.K).

A small point of correction -  it was not a hammer that sprung into existence above the Dragon's head but a giant scythe. As the dragon tries to avoid the scythe a cloud of various grains and nuts starts raining down on it - Aze the Magnificent's save = (DC 15 = 10). While most of the nuts and grains don't do much damage, the coco de mer nuts - which can weigh up to 25 kg - do cause the dragon a few bruises.

Devin - its your turn

Devin concentrated on the blessing he gave his companions and then started his own assault on the dragon.  "I have no interest in being anyone's slave, Begone!" he yells as he throws a molt of fire at the dragon Fire Bolt

Attack: 24 Damage: 6 fire damage

He then conjures up a Spiritual Weapon in the form of a blue star next to the dragon and slams it into the dragon

Attack: 23 Damage: 7 force damage

Mullo - you're up

Mullo maneuvers so that she has a direct path to the dragon and yells, "Puny wyrm! Feel the wrath of this Sky Pony!" The air around her crackling, she points a finger at the creature and bolt of lightning streaks at it.

lightning bolt  - DC15 DEX save or take 48 lightning damage (full damage due to using channel divinity) or half on save

Mullo judges when the dragon is effectively isolated and summoning the wrath of her god sends a bolt of lightning speeding towards the dragon (DC 15 [Dex] = 24)

Illezenya - you're up

(Soothing Twilight - 8 rounds left. My companions within 30' and I can gain 9 temporary hps.)

"Begone, wyrm. You shall find nothing here but pain," Ilezenya says to the dragon as a sonorous bell sounds in the distance. (Action - Toll the Dead - DC15 Wis save or take 14 necrotic) The Dusk Warden's spiritual weapon continues to attack the dragon. (Bonus action -  Attack: 10 Damage: 12. 

Aze's save against the bells of death (DC 15 [Wis] = 24

As the death bells ring out, the dragon disengages from the battle and launches itself off the port side of the airship - quickly reaching its full speed. As it leaves it bellows "I'll be back when you least expect it groundlings!"

The cultist who had been beating his head against the deck in submission takes the opportunity to leap to his feet and make a beeline for the hatch and clambers down slamming it shut after himself.

Them party can now hear nothing but the wind whistling in the rigging.

Ebonitus quickly moves across to the nearest fallen crewman to check for signs of life. He then continues to the others. If any can be saved, he will heal them.

Ilezenya gets his bearings and then grabs the helm, attempting to steer the vessel towards their objective!

Haetone lands on deck, and Mullo dismounts in a rush. "Does anyone need healing? How are the strangers?"